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Cell Membranes and Compartments
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Introduction
A major difference between eukayotes and prokaryotes is
the presence of physical compartments (membrane bound)
within the cell. These compartments allow the
separation/specialization of processes within the cell.
There also exist within each of these physical
compartments, functional compartments where specific
processes may occur or are restricted too. This lecture is
an introduction to compartments within the cell and
membranes. The key components are: cell compartments,
membrane structure, membrane models, membrane
specializations.
2017 Lecture PDF
Eukaryotic Cell Physical Compartments
Lecture Archive: 2016
(https://cellbiology.med.unsw.edu.au/cellbiology/index.php?
title=Cell_Membranes_and_Compartments&oldid=58465) | 2015
(http://php.med.unsw.edu.au/cellbiology/index.php?
title=Cell_Membranes_and_Compartments&printable=yes) | 2014
(http://php.med.unsw.edu.au/cellbiology/index.php?
title=Cell_Membranes_and_Compartments&oldid=48070) | 2013
(http://php.med.unsw.edu.au/cellbiology/index.php?
Membrane cartoon
title=Cell_Membranes_and_Compartments&oldid=42439) 2012
(http://php.med.unsw.edu.au/cellbiology/index.php?
title=Cell_Membranes_and_Compartments&oldid=32154) | 2010 | 2009 | 2008
(http://cellbiology.med.unsw.edu.au/units/science/lecture0803.htm) | 1/page 2007 (viewing only) 43 pages, 1.4 Mb
(http://cellbiology.med.unsw.edu.au/units/pdf/ANAT3231L2s1.pdf)
Objectives
Understand the concept of separate intracellular spaces
Understand the structure of membranes
Brief understanding of history of membrane models
Understand the difference between physical and functional compartments
Brief understanding of membrane specializations
History
Robert Hooke (1635-1703)
used early microscopes to view cork tree bark
was the first to use the term CELL
Robert Brown 1825
identified nuclei in plant cells
Theodor Schwann (1810 - 1882)
together with Matthias Schleiden (plants) developed the cell theory in 1839
Cell Theory
All organisms consist of one or more cells
The cell is the basic unit of structure for all cells
All cells arise only from preexisting cells
Plasma Membrane Images
The cell membrane (plasma membrane or plasmalemma) encloses or covers all cell types and is 7 nanometers (7 x 109 M)
thick. Begin by some different ways of looking microscopically at membranes.
Membrane - Light Micrograph
Membrane - Fluorescent Micrograph
Cork Bark by Robert Hooke 1665
Yeast - Candida albicans
R T Watson, S Shigematsu, S H Chiang, S Mora, M Kanzaki, I G Macara, A
R Saltiel, J E Pessin Lipid raft microdomain compartmentalization of
TC10 is required for insulin signaling and GLUT4 translocation. J. Cell
Biol.: 2001, 154(4);829-40 PubMed 11502760
Membrane - Scanning Electron Micrograph
thickness 3.5 nm
Membrane - Transmission Electron Micrograph
Links: Block-Face Scanning Electron Microscopy to Reconstruct Three-Dimensional Tissue Nanostructure
(http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0020329%7CSerial) Denk W,
Horstmann H (2004) Serial Block-Face Scanning Electron Microscopy to Reconstruct Three-Dimensional Tissue
Nanostructure. PLoS Biol 2(11): e329
Compartments
Physical Compartments
membrane bound
Nucleus, Cytoplasm, Organelles
cell nomenclature based upon presence or
absence of these compartments (eukaryotic,
prokaryotic)
Functional Compartments
spatial localization
targeting
activation and inactivation
signaling
Major Cellular Compartments
Nucleus (nuclear) contains a single
Eukaryotic Cell Physical Compartments
organelle
compartment
Cytoplasm (cytoplasmic) - contains many organelle compartments
Organelle Number/Volume
How many organelles?
How much space within the cell do they occupy?
Are all the cells the same?
Proposed model for organelle
membrane evolution
Take a typical mammalian liver cell....
Liver Structure (http://www.ncbi.nlm.nih.gov/books/bv.fcgi?
highlight=hepatocyte&rid=mboc4.figgrp.4123)
Table 12-1. Relative Volumes Occupied by the Major Intracellular Compartments in a Liver Cell (Hepatocyte)
(http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=hepatocyte&rid=mboc4.table.2135)
Table 12-2. Relative Amounts of Membrane Types in Two Kinds of Eucaryotic Cells
(http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=hepatocyte&rid=mboc4.table.2136)
Compartments are Dynamic
Movies showing flexibility of membranes and their changing shape and size.
​Microfilaments
Page | Play
​Adhesion Integrin
Page | Play
http://www.ncbi.nlm.nih.gov/books/NBK21687/figure/A4101
Fluidity of the Lipid Bilayer (http://www.garlandscience.com/garlandscience_resources/resource_detail.jsf?
landing=student&resource_id=9780815341291_CH11_QTM01)
Nuclear Compartment
Nuclear matrix - consisting of Intermediate filaments (lamins)
Nucleoli (functional compartment - localised transcription DNA of RNA genes)
Chromosomes (DNA and associated proteins)
(MH - you will not see chromosomes in interphase nuclei only during mitosis, more in the Nucleus Lecture)
Cytoplasmic Compartment
Cytoplasmic Organelles
Membrane bound structures
Endoplasmic reticulum, golgi apparatus, mitochondria, lysosomes, peroxisomes, vesicles
Cytoskeleton
3 filament systems
Cytoplasmic “structures”
Ribosomes
DNA -> mRNA -> Protein
Proteins
Receptors, signaling, metabolism, structural
Viruses, bacteria, prionsl
Functional compartments
occur in nucleus, cytoplasm, in organelles and outside organelles
signaling, metabolic reactions, processing genetic information, cytoskeleton dynamics, vesicle dynamics
Membrane Functions
Form compartments
Allow “specialization”
Metabolic and biochemical
Localization of function
Regulation of transport
Detection of signals
Cell-cell communication
Cell Identity
Plasma Membrane Image
Cell (Plasma) encloses or covers or cell types.
EM - Cell (Plasma) and Organelle Membranes
Cell (Plasma) and Organelle Membranes
Membrane Components
phospholipids, proteins and cholesterol
first compartment formed
prokaryotes (bacteria) just this 1 compartment
eukaryotic cells many different compartments
Membrane size
Phospholipids
Polar Head
Choline
|
membranes contain phospholipids, glycolipids, and steroids
Phosphate
The main lipid components include:
|
phosphatidylcholine (~50%)
Glycerol
phosphatidylethanolamine (~10%)
12
phosphatidylserine (~15%)
CH2 CH2
sphingolipids (~10%)
CH2 CH2
cholesterol (~10%)
phosphatidylinositol (1%).
CH2 CH2
CH2 CH2
Non-Polar Hydrocarbon Tail
Amphipathic - having both hydrophilic and hydrophobic properties. (phospholipids, cholesterol, glycolipids).
Links: Three views of a cell membrane (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=Books&rid=mboc4.figgrp.1862) |
MCB Schematic diagram of typical membrane proteins in a biological membrane
(http://www.ncbi.nlm.nih.gov/books/NBK21570/figure/A609)
Phospholipid Orientation
Figure 2-22. Phospholipid structure and the orientation of phospholipids in membranes
(http://www.ncbi.nlm.nih.gov/books/bv.fcgi?&rid=mboc4%2Efiggrp%2E211)
A liposome (lipid vesicle) is a small aqueous compartment
surrounded by a lipid bilayer.
A micelle is a small compartment surrounded by a single lipid
layer.
Membranes History
1890 Charles Overton
selective permeation of membranes
Phospholipid Bilayer
non-polar pass through (lipid soluble)
polar refractory
lipids present as a coat
1905 Irving Langmuir
lipids faced with heads towards water away from organic solvents
1925 Gorter and Grendel
monolayer of lipid isolated from rbc
twice (2x) surface area of cell (bilayer)
1930-40 Danielle-Davson
Proteins coat a bilayer with polar “pores”
1960s Robertson
Modification with glycoprotein on one side, therefore
asymmetric
1972 Singer and Nicholson
proteins “floating” within lipid bilayer like a “liquid”
surface
1975 Unwin and Henderson
integral membrane proteins
both hydrophobic and hydrophilic
alternating -phobic and -philic represent trans-membrane
loops
glycoprotein carbohydrate groups on outer surface
Links: MCB - Freeze fracturing can separate the two
phospholipid leaflets that form every cellular membrane
Phospholipid Orientation
(http://www.ncbi.nlm.nih.gov/books/NBK21583/figure/A1166/) | MCB - Solubilization of integral membrane proteins
by nonionic detergents (http://www.ncbi.nlm.nih.gov/books/NBK21589/figure/A631/)
Membranes Recent History
1997 Simons - cholesterol to form rafts that move within the fluid
bilayer
“Membrane Rafts” “A new aspect of cell membrane structure is
presented, based on the dynamic clustering of sphingolipids and
cholesterol to form rafts that move within the fluid bilayer. It is
proposed that these rafts function as platforms for the attachment of
proteins when membranes are moved around inside the cell and
during signal transduction.”
saturated lipids and cholesterol form liquid-ordered domains
Lipid rafts
Morphology and_ interaction between lipid domains
Cartoon of different raft roles (http://jcs.biologists.org/content/118/6/1099/F1.large.jpg)
Links: PMID20044567 (http://www.ncbi.nlm.nih.gov/pubmed/20044567) | Fig. 1 Evolution of the raft concept for
subcompartmentalization in cell membranes (http://www.sciencemag.org/content/327/5961/46/F1.large.jpg)
Membrane Proteins
Protein Layer-Lipid-Protein Island Model
Outside
Inside
Links: Protein Layer-Lipid-Protein Island Model | Membrane size | Outside | Inside | PMID 24806512
20-30% of the genome encodes membrane proteins PMID 9568909
Proteins can be embedded in the inner phospholipid layer, outer phospholipid layer or span both layers
Some proteins are folded such that they span the membrane in a series of “loops”
Two major protein transmembrane structures
1. α-helical - ubiquitously distributed
2. β-barrel - outer membranes of Gram-negative bacteria, chloroplasts, and mitochondria
Membrane Protein Functions
transport channels
enzyme reactions
cytoskeleton link
cell adhesion
cell identity
Links: MCB Topologies of some integral membrane proteins synthesized on the rough ER
(http://www.ncbi.nlm.nih.gov/books/NBK21731/figure/A4776/)
Membrane Glycoproteins
Glycoproteins are proteins which have carbohydrate groups (sugars) attached
to produce these proteins go through a very specific cellular pathway of organelles (secretory pathway)
to reach the cell surface where they are either secreted (form part of the extracellular matrix)
or are embedded in the membrane with the carbohydrate grouped on the outside surface (integral membrane protein)
distribution of glycoproteins have functional effects (motility, migration, channel distribution, signalling) PMID
24040379
Membrane Cholesterol
Small molecule embedded between the phospholipid molecules and regulates lipid mobility (MH - see rafts)
Cholesterol can be at different concentrations in different regions of plasma
membrane
lateral organization of membranes and free volume distribution
may control membrane protein activity and "raft” formation
fine tuning of membrane lipid composition, organization/dynamics, function
bacterial membranes (except for Mycoplasma and some methylotrophic bacteria)
have no sterols, they lack the enzymes required for sterol biosynthesis.
Model of Cell (plasma) membrane
structure
Links: MBoC Figure 10-9. Cholesterol in a lipid bilayer
(http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=cholesterol&rid=cell.figgrp.2458)
Bacterial Membranes
(MH - covered this in previous Lecture)
Bacteria with double membranes (Example: E. coli)
inner membrane is the cell's plasma membrane
Gram Negative do not retain dark blue dye used in gram staining
Bacteria with single membranes (Example: staphylo-cocci and streptococci)
thicker cell walls
Gram Positive because they do retain blue dye
single membrane comparable to inner (plasma) membrane of gram negative bacteria
Membrane Fluidity
fusion of 2 cells
FRAP
membrane domains (polarized cells)
epithelia - apical, basal and lateral domains
Tubular Bridges
Neutrophil activation membrane reorganisation
(cytonemes and tunneling nanotubes, TNTs) - New membrane structures
identified that can facilitate transfer of cellular signals and components
over large distances (hundreds of microns) representing the longest direct
connections between cells in vitro and in vivo.
File:Bronchial epithelial bridge.mov
Tubular Bridges for Bronchial Epithelial Cell Migration and
Communication
Bronchial epithelial bridge
(http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0008930) Membrane structures
​Exocytosis
Page | Play
J F Presley, N B Cole, T A Schroer, K
Hirschberg, K J Zaal, J Lippincott-Schwartz
ER-to-Golgi transport visualized in living
cells. Nature: 1997, 389(6646);81-5 PubMed
9288971
Links: FRAP (http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=FRAP&rid=mcb.figgrp.1162) | MBC - Membrane
Fluidity (http://www.ncbi.nlm.nih.gov/books/bv.fcgi?highlight=Membrane%20Proteins&rid=mcb.figgrp.1161)
Membrane Specializations
plasma membrane
cytoskeleton
different directly
under membranes
adhesion
complexes
absorbtive and
secretory
synaptic junctions
fenestrations
This range of membrane
specializations will be
covered in detail in later
Lectures.
Super resolution imaging of Liver sinusoidal endothelial cell (LSEC) fenestrations.[1]
Liver sinusoidal endothelial cells (LSECs)[2] act as a filter between blood and the hepatocytes and
are highly fenestrated cells (contain transcellular pores with diameters between 50 to 200 nm). The
small sizes of the fenestrae have so far prohibited any functional analysis with standard and
advanced light microscopy techniques.
labeled LSEC movie
Adhesion Specializations
A series of different types of proteins and cytoskeleton associations forming different classes of adhesion junctions (MH covered in detail in a lecture 8)
Desmosomes ( = macula adherens)
Adherens Junctions ( = zonula adherens)
Septate Junctions
Tight Junctions
Gap Junctions
Covered in Cell Junctions
Membrane Transport
Three major forms of transport across the membrane
Passive - Simple diffusion
Facilitated - transport proteins
Active - transport proteins for nutrient uptake, secretion, ion balance
Links: Figure 17-13The secretory pathway of protein synthesis and sorting
(http://www.ncbi.nlm.nih.gov/books/NBK21471/figure/A4740/)
Ion Channels
phospholipid impermeable to ions in aqueous solution
protein channels permit rapid ion flux
1960’s structure and function, ionophores (simple ion channels)
common structural motif alpha helix
75 + different ion channels
Allosteric proteins - conformation regulated by different stimuli
opening/closing, “gating” of ions
Ion Channel Types
3 rapid + 1 slow gate (gap junction)
Voltage-gated - propogation of electrical signals along nerve,
muscle
Ligand-gated - opened by non-covalent, reversible binding of
ligand between nerve cells, nerve-muscle, gland cells
Mechanical-gated - regulated by mechanical deformation
Gap junction - allow ions to flow between adjacent cells
open/close in response to Ca2+ and protons
Apoptosis and Membranes
programmed cell death
membrane "blebbing" encloses cellular component fragments
Cell potassium channels
Link: Time-lapse movie of human HeLa cells undergoing apoptosis
(http://www.nature.com/nrm/journal/v9/n3/extref/nrm2312-s1.mov) PMID: 18073771
(http://www.ncbi.nlm.nih.gov/pubmed/18073771?) | Example of early apoptotic blebbing
(http://jcs.biologists.org/content/vol118/issue17/images/data/4059/DC1/JCS14488Video1.mov) PMID:16129889
(http://www.ncbi.nlm.nih.gov/pubmed/16129889?)
Membrane Transport Disease
Cystic Fibrosis
1989 Collins (US), Tsui and Riordan (Canada)
Chloride channel protein mutation
point mutant, folded improperly, trapped and degraded in ER
Historic Papers
Below are some example historical research finding related to cell membranes from the JCB Archive and other sources.
1957 The invention of freeze fracture EM and the determination of membrane structure
(http://jcb.rupress.org/cgi/content/full/168/2/174-a) Russell Steere introduces his home-made contraption for freeze fracture
electron microscopy (EM), and Daniel Branton uses it to conclude that membranes are bilayers.
1971 Spectrin is peripheral (http://www.jcb.org/cgi/doi/10.1083/jcb1701fta1) S. Jonathan Singer, Garth Nicolson, and Vincent
Marchesi use red cell ghosts to provide strong evidence for the existence of peripheral membrane proteins.
1992 Lipid raft idea is floated (http://jcb.rupress.org/cgi/content/full/172/2/166) Gerrit van Meer and Kai Simons get the first
hints of lipid rafts based on lipid sorting experiments.
Links: Sorted JCB Archive -Membranes JCB Archive (http://jcb.rupress.org/misc/fromthearchive.shtml)
1. Viola Mönkemöller, Cristina Øie, Wolfgang Hübner, Thomas Huser, Peter McCourt Multimodal super-resolution
optical microscopy visualizes the close connection between membrane and the cytoskeleton in liver sinusoidal
endothelial cell fenestrations. Sci Rep: 2015, 5;16279 PubMed 26549018
2. Viola Mönkemöller, Cristina Øie, Wolfgang Hübner, Thomas Huser, Peter McCourt Multimodal super-resolution
optical microscopy visualizes the close connection between membrane and the cytoskeleton in liver sinusoidal
endothelial cell fenestrations. Sci Rep: 2015, 5;16279 PubMed 26549018
References
Textbooks
Molecular Biology of the Cell
Chapter 10 - Membrane Structure (http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cell&part=A2443)
Three views of a cell membrane (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=mboc4.figgrp.1862)
The evolution of higher animals and plants (Figure 1-38) (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=cell.figgrp.83)
From Procaryotes to Eucaryotes (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=cell.section.25#60)
From Single Cells to Multicellular Organisms (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=cell.section.61#82)
Some of the different types of cells present in the vertebrate body
(http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=Books&rid=cell.box.79)
Molecular Cell Biology
The Dynamic Cell (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=Books&rid=mcb.chapter.145)
The Architecture of Cells (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=&rid=mcb.section.203)
Microscopy and Cell Architecture (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=mcb.section.1084)
The Cell- A Molecular Approach
An Overview of Cells and Cell Research (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?
db=Books&rid=cooper.chapter.89)
Tools of Cell Biology (http://www.ncbi.nlm.nih.gov:80/books/bv.fcgi?db=Books&rid=cooper.section.128)
Search Online Textbooks
"cell compartments" Molecular Biology of the Cell (http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?
db=Books&cmd=search&doptcmdl=DocSum&term=cell+compartments+AND+mboc4%5Bbook%5D) | Molecular
Cell Biology (http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?
db=Books&cmd=search&doptcmdl=DocSum&term=cell+compartments+AND+mcb%5Bbook%5D) | The Cell- A
molecular Approach (http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?
db=Books&cmd=search&doptcmdl=DocSum&term=cell+compartments+AND+cooper%5Bbook%5D)
"cell membrane" Molecular Biology of the Cell (http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?
db=Books&cmd=search&doptcmdl=DocSum&term=cell+membrane+AND+mboc4%5Bbook%5D) | Molecular Cell
Biology (http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?
db=Books&cmd=search&doptcmdl=DocSum&term=cell+membrane+AND+mcb%5Bbook%5D) | The Cell- A
molecular Approach (http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?
db=Books&cmd=search&doptcmdl=DocSum&term=cell+membrane+AND+cooper%5Bbook%5D)
Books
The Cytoskeleton - cellular architecture and choreography (http://books.google.com/books?id=JNHuxHzTm7IC)
Reviews
Vertebrate membrane proteins: structure, function, and insights from biophysical approaches. Müller DJ, Wu N, Palczewski
K. Pharmacol Rev. 2008 Mar;60(1):43-78. Epub 2008 Mar 5. Review. PMID: 18321962
Articles
Studying the Nucleated Mammalian Cell Membrane by Single Molecule Approaches (http://journals.plos.org/plosone/article?
id=10.1371/journal.pone.0091595)
Images
Protein Layer-LipidProtein Island (PLLPI)
model of the cell
membrane
Protein Layer-LipidProtein Island (PLLPI)
model of the cell
membrane
Protein Layer-LipidProtein Island (PLLPI)
model of the cell
membrane
Protein Layer-LipidProtein Island (PLLPI)
model of the cell
membrane
Proposed model for
organelle membrane
evolution
Model of Cell (plasma)
membrane structure
Model of Exocytosis
Caveolae EM as part of
mechanisms also
membrane turnover
showing new membrane
turnover.
Membrane Terms
adhesion junction membrane specialization allowing either cell-cell or cell-extracellular matrix adhesion generally in
multicellular organisms.
bilayer having two layers, refers to the 2 lipid layers of a single membrane.
blebbing a plasma membrane change often associated with apoptosis. The underlying cell cytoskeleton is disrupted
leading to a the bubbling of the plasma membrane, which will enclose cytoplasmic and nuclear components.
cholesterol small steroid metabolite that decreases membrane motility involved in many membrane functions
(endocytosis, membrane rafts). Bacterial membranes (except for Mycoplasma and some methylotrophic bacteria) have
no sterols, they lack the enzymes required for sterol biosynthesis.
cytonemes thin, actin-based extensions that project from cells and allow cell-cell communication.
electron microscopy a microscope technique that uses beams of electrons instead of light to generate high resolution
images of cellular components. This technique historically gave the first images of the membrane bilayer structure.
electron tomography an electron microscopic technique to generate a three dimensional (3-D) image from any electron
microscopy specimen.
exosomes small vesicles that bud from the endosome membrane into its lumen. Following endosome fusion with the
plasma membrane, the exosomes are released into the extracellular space.
http://jcb.rupress.org/cgi/content/full/172/6/785?
flippases enzymes that catalyze rapid translocation of phospholipids across the endoplasmic reticulum membrane.
Required for balanced growth of both halves of the bilayer.
flotillin (flotillin-1 and -2) protein that is ubiquitously enriched in detergent resistant membranes (membrane rafts).
functional compartment a specialized region formed within a cell which is not limited by a membrane, compared to a
"structural compartment".
Gram negative term used to describe bacteria which do not retain the Gram dye when stained. These are bacteria with
double membranes, the inner membrane is the cell's plasma membrane (Example: E. coli).
Gram positive term used to describe bacteria which do retain the Gram dye when stained. These are bacteria with
single membranes and thicker cell wall (Example: staphylo-cocci and streptococci).
lipids the basic molecules forming the lipid bilayer as phospholipids, glycolipids, and steroids. The main lipid
components include phosphatidylcholine (~50%), phosphatidylethanolamine (~10%), phosphatidylserine (~15%),
sphingolipids (~10%), cholesterol (~10%), and phosphatidylinositol (1%). Medical Microbiology - Plasma
(Cytoplasmic) Membranes (http://www.ncbi.nlm.nih.gov/books/bv.fcgi?
highlight=plasma%20membrane&rid=mmed.section.305#306)
liposome (lipid vesicle) is a small aqueous compartment surrounded by a lipid bilayer.
membrane cytoskeleton the components of the cell cytoskeleton that directly underly either the cell (plasma) and
nuclear membranes.
micelle is a small compartment surrounded by a single lipid layer.
phospholipid the basic molecule forming the lipid bilayer of a typical membrane (see also lipid).
raft (lipid rafts, membrane raft) term used to describe stabilized regions that form within membranes. These rafts
"float" within the lipid membrane and are formed by cholesterol altering (stabilizing) the fluidity of the local membrane.
structural compartment a specialized region formed within a cell which is limited by a membrane, compared to a
"functional compartment".
trogocytosis process of T and B cells capture antigens via membrane fragments of antigen presenting cells (APC).
vesicle general term given to any membrane enclosing material within the cytoplasm.
protein-to-lipid ratio the analysis of membranes by separating the 2 main components. For example, bacterial plasma
membranes are approximately 3:1, close to those for mitochondrial membranes.
External Links
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function.
If the link no longer works search the web with the link text or name.
American Society Cell Biology (http://www.ascb.org/)
American Society Cell Biology - Booklet Exploring the Cell (http://www.ascb.org/files/exploring.pdf)
The Nobel Prize in Physiology or Medicine - Laureates (http://www.nobel.se/medicine/laureates/)
People
Berkeley History - Robert Hooke (1635-1703) (http://www.ucmp.berkeley.edu/history/hooke.html)
Berkeley History - Antony van Leeuwenhoek (http://www.ucmp.berkeley.edu/history/leeuwenhoek.html)
Robert Brown (http://www.whonamedit.com/doctor.cfm/2539.html)
Theodor Schwann (http://home.tiscalinet.ch/biografien/biografien/schwann.htm)
Matthias Schleiden (1804-1881)
Museum of Microscopy (http://microscopy.fsu.edu/primer/museum/)
The WWW Virtual Library of Cell Biology- General Cell Biology
(http://vlib.org/Science/Cell_Biology/general_cell_biology.shtm)
The Biology Project- Studying Cells (http://www.biology.arizona.edu/cell_bio/tutorials/cells/cells2.html)
2003 Double Helix Celebrations (http://www.dna50.org/main.htm)
Genome Timeline (http://www.genomenewsnetwork.org/timeline/timeline_overview.shtml)
Movies
JCB
A marker for sequential exocytosis The SNARE protein SNAP25, say Takahashi et al.
(http://jcb.rupress.org/cgi/content/abstract/165/2/255), marks the plasma membrane after an initial exocytic event to
allow rapid sequential exocytic events (http://jcb.rupress.org/cgi/content/full/jcb.200312033/DC1/1).
A myosin V moves yeast secretory vesicles Secretory vesicles actively move
(http://jcb.rupress.org/cgi/content/full/jcb.200110086/DC1/1) to the site of exocytosis in yeast. Schott et al.
(http://jcb.rupress.org/cgi/content/abstract/156/1/35) find that multiple secretory vesicles often follow the same linear
track (http://jcb.rupress.org/cgi/content/full/jcb.200110086/DC1/2) and frequently enter and cross the bud. This
movement requires (http://jcb.rupress.org/cgi/content/full/jcb.200110086/DC1/3) the activity of the myosin-V heavy
chain encoded by the MYO2 gene. When the predicted lever arm of this motor is progressively shortened (with the most
extreme example being the 0IQ mutant), the vesicle movements are progressively slowed
(http://jcb.rupress.org/cgi/content/full/jcb.200110086/DC1/4).
Rapid cycling of lipid rafts to and from the Golgi Nichols et al. (http://jcb.rupress.org/cgi/content/abstract/153/3/529)
detect rapid cycling of lipid raft markers between the plasma membrane and the Golgi. Through selective
photobleaching, they are able to study transport either out from the Golgi
(http://jcb.rupress.org/cgi/content/full/153/3/529/F3/DC2) to the plasma membrane, or in from the plasma membrane
(http://jcb.rupress.org/cgi/content/full/153/3/529/F5/DC1) to the Golgi.
Membrane docking at the immunological synapse requires Rab27a Stinchcombe et al
(http://jcb.rupress.org/cgi/content/abstract/152/4/825). find that normal membrane docking
(http://jcb.rupress.org/cgi/content/full/152/4/825/F6/DC2) of lytic granules at the immunological synapse is defective in
cells lacking Rab27a. In cells lacking other Rab proteins, polarization of the secretory granules is incomplete
(http://jcb.rupress.org/cgi/content/full/152/4/825/F6/DC4).
Visualizing the location and dynamics of exocytosis Schmoranzer et al.
(http://jcb.rupress.org/cgi/content/abstract/149/1/23) use total internal reflection (TIR) fluorescence microscopy to
visualize exocytosis (http://jcb.rupress.org/cgi/content/full/149/1/23/F2/DC1) in mammalian cells (e.g., see event on left
side of video). The analysis reveals that there are no preferred sites for constitutive exocytosis in this system.
Visualizing the location and dynamics of exocytosis Toomre et al.
(http://jcb.rupress.org/cgi/content/abstract/149/1/33) use a combination of TIR microscopy (green, labeling molecules
close to or at the membrane) and standard fluorescence microscopy (red, for molecules further from the membrane) to
visualize trafficking to and fusion with
(http://jcb.rupress.org/cgi/content/vol149/issue1/images/data/33/DC1/Fig_1b.mov) the plasma membrane during
exocytosis. Red dots turn yellow then green as they approach the membrane, and then explode in a burst of light as they
fuse with the plasma membrane during exocytosis. The transport containers appear to be partially anchored at the
membrane before fusion, and can undergo either partial or complete fusion events.
PLoS Movies
File:Membrane label and endosomes.mov
Dynamic Changes in the Spatiotemporal Localization of Rab21 in Live RAW264 Cells during Macropinocytosis
(http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006689)
Ordered Patterns of Cell Shape and Orientational Correlation during Spontaneous Cell Migration
(http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0003734)
From Dynamic Live Cell Imaging to 3D Ultrastructure: Novel Integrated Methods for High Pressure Freezing and
Correlative Light-Electron Microscopy
(http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0009014)
Online Movies
SoftSimu Movie Gallery (http://www.apmaths.uwo.ca/~mkarttu/gallery-movie.shtml)
Structure of Fluid Lipid Bilayers (http://blanco.biomol.uci.edu/Bilayer_Struc.html)
Changes in cholesterol levels in the plasma membrane modulate cell signaling and regulate cell adhesion and migration
on fibronectin (http://www3.interscience.wiley.com/journal/114068500/suppinfo)
Neuronal growth cones (http://jcs.biologists.org/cgi/content/full/121/22/3757/DC1)
2017 Course Content
Lectures: Cell Biology Introduction | Cells Eukaryotes and Prokaryotes | Cell Membranes and
Compartments | Cell Nucleus | Cell Export - Exocytosis | Cell Import - Endocytosis | Cytoskeleton
Introduction | Cytoskeleton - Microfilaments | Cytoskeleton - Microtubules | Cytoskeleton - Intermediate
Filaments | Cell Mitochondria | Cell Junctions | Extracellular Matrix 1 | Extracellular Matrix 2 | Cell
Cycle | Cell Division | Cell Death 1 | Cell Death 2 | Signal 1 | Signal 2 | Stem Cells 1 | Stem Cells 2 |
Development | 2017 Revision
2017 Laboratories: Introduction to Lab | Fixation and Staining |
2017 Project Topics - TBD.
Dr Mark Hill 2015, UNSW Cell Biology - UNSW CRICOS Provider Code No. 00098G
Moodle
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Categories: Science-Undergraduate 2017ANAT3231
This page was last modified on 14 March 2017, at 08:54.