Download Cell Junctions II

Cell Junctions and
extra cellular matrix II
chapter 19
Desmosomes and hemidesmosomes both link to
intermediate filaments
Cadherins also bind intermediate filaments together
Integrins link extracellular matrix to cytoskeleton
Size of gap junction channel can be determined
with fluorescent molecules of different sizes
A Gap junction connexon is made up of 6
transmembrane connexin subunits
Images of gap junctions
The permeability of gap junctions can be regulated
dopamine treatment reduces permeability of gap junctions to a fluorescent dye
Summary of cell junctions found in the cell
Summary of cell junctions found in the cell
In plant cells plasmodesmata perform many of
the same functions as gap junctions
View of plasmodesmata
Structure of Cadherin – responsible for cell to
cell adhesion in vertebrate cells
Ca2+ is required to establish cell to cell
connection through cadherin
Three mechanisms that mediate cell-cell
adhesion
cadherins
least common
Cadherins allow cells to sort themselves
Catenins join cadherins to actin filaments in
adherence junctions
Summary of junctional and non-junctional
adhesive mechanisms
Cells surrounded by extracellular matrix
Cross sectional view of intestinal wall
Connective tissue underlying the epithelium contains a
variety of cells and extracellular matrix components
Fibroblasts surrounded by collagen fibrils
Glycosaminoglycan (GAG) chains occupy large
amounts of space and form hydrated gels
Hyaluronan, a simple GAG, occupies a large amount
of space, thereby providing mechanical support
Repeating disaccharide unit of hyaluronan
GAG and its core protein form proteoglycan
Comparison of proteoglycans with a ribonuclease
picture of aggrecan aggregate, a large
proteoglycan
structure of Aggrecan aggregate
Collagen fibril embedded in proteoglycan molecules
Fibroblast surrounded by collagen fibrils
Collagen fibrils in tadpole skin
This arrangement
is also found in
bone and the
cornea
Elastic fibers in a dog’s aorta
Each elastin protein in the network can expand
and contract as a coil
Fibronectin is an extracellular protein that helps
cells attach to the matrix
Connective tissue underlying the epithelium contains a
variety of cells and extracellular matrix components
basal lamina in the cornea of a chick’s embryo
A model of the basal lamina
Cross Section of Kidney
Filtration is one step in urine formation
Structure of Nephrons
Inside Bowman’s Capsule
Basal Lamina plays an important role in filtration