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Transmitter Release
Transmitter Release

Rab Proteins and the Organization of Organelle Membrane Domains
Rab Proteins and the Organization of Organelle Membrane Domains

... the largest interactome of any individual small GTPase family member described so far (Christoforidis et al. 1999a). Indeed, several of these effector molecules act coordinately and cooperatively with other components of the transport machinery. For example, the localized synthesis of phosphatidylin ...
REVIEWS
REVIEWS

Mechanisms of transport through the Golgi complex
Mechanisms of transport through the Golgi complex

... C-terminus of GMAP-210 contains a GRAB domain (yellow) that binds to membranes containing Arf1-GTP (red circles). In the absence of highly curved membranes, the N-terminal ALPS motif (orange) of GMAP-210 is unstructured. When the ALPS motif comes into contact with a highly curved membrane such as a ...
ref. #27 of the TIBS article
ref. #27 of the TIBS article

... MGD and n for a protein that does not use this pathway. Synaptobrevin is known to insert a hydrophobic C-terminal segment into the microsomal membrane by an as yet poorly understood mechanism that does not involve the SRP/Sec61 machinery (Kutay et al., 1995), and it can be glycosylated on its lumena ...
Increased Susceptibility of the Sickle Cell Membrane
Increased Susceptibility of the Sickle Cell Membrane

PHOSPHOLIPIDS AND BIOMEMBRANES L. L. M. VAN DEENEN
PHOSPHOLIPIDS AND BIOMEMBRANES L. L. M. VAN DEENEN

... tncomplex system between phospholipids, proteins and cations. Many other approaches further endorsed the importance of phospholipids for attaining the physical and chemical arrangements required to give the bio-interfaces their remarkable properties. Sub-cellular components, consisting of membranes ...
Effects of Single Amino Acid Substitution on the Biophysical
Effects of Single Amino Acid Substitution on the Biophysical

DIFFERENT MODES OF FLUORESCENTLY LABELED
DIFFERENT MODES OF FLUORESCENTLY LABELED

Dual-topology membrane proteins Escherichia coli  Susanna Seppälä
Dual-topology membrane proteins Escherichia coli Susanna Seppälä

... With the exception of archaeal monolayers, a typical biological membrane is based on two layers of lipid molecules. Common membrane lipids are phospholipids, galactolipids, sphingolipids and sterols; their most conspicuous feature being an extended hydrophobic part carrying a hydrophilic headgroup ( ...
Review Article GPCRs: Lipid-Dependent Membrane Receptors That
Review Article GPCRs: Lipid-Dependent Membrane Receptors That

fulltext - DiVA Portal
fulltext - DiVA Portal

... functionally very important part of every cell. The membrane forms not only a barrier that seal out the cell’s external environment and so defines its boundary, but also mediates the selective exchange of information and substances. Furthermore, membranes are the sites where key steps of many vital ...
isolation and characterization of the membrane
isolation and characterization of the membrane

... The membrane envelope enclosing the bacteroids in soybean root nodules is shown by ultrastructural and biochemical studies to be derived from, and to retain the characteristics of, the host cell plasma membrane. During the early stages of the infection process, which occurs through an invagination, ...
Intermediary Metabolism and Life-History Trade
Intermediary Metabolism and Life-History Trade

... et al. 1976; Zera et al. 1997). Except in a few rare cases, all short-winged females molt into adults with white, nonfunctional, underdeveloped flight muscles. All longwinged females initially have fully developed (pink) flight muscles at or shortly after the adult molt (denoted LW(f )); however, fl ...
Detection, Characterization, and Bioavailability of Membrane
Detection, Characterization, and Bioavailability of Membrane

... In providing a permeability barrier for cell membranes, nature has used phospholipids that are partially unsaturated and has concomitantly employed a variety of protective mechanisms to limit the access of iron to lipid. Examples include the high affinity association of iron with various chelators, ...
Sensory TRP Channel Interactions with Endogenous Lipids and
Sensory TRP Channel Interactions with Endogenous Lipids and

... and chemical changes, or in another way, as external and internal ones. Chemical changes, particularly, which includes substances released near sensory nerve terminals, can encompass the majority of internal environmental changes. Examples of those substances include cellular components like nucleot ...
Molecular Affinity and Permeability of Different Molecular Weight
Molecular Affinity and Permeability of Different Molecular Weight

ref. #28 of the TIBS article
ref. #28 of the TIBS article

... the H-subunit of the photosynthetic reaction center can be used as a reference helix against which the membrane position of other TMHs can be determined (Nilsson et al., 1998). In order to extend our set of reference TMHs and, in particular, in order to determine the MGD for a TMH with known positio ...
Dissecting sterol function during clathrin-dependent
Dissecting sterol function during clathrin-dependent

... lipid bilayer solvent that can interact with peripheral proteins (Simons and Sampaio, 2011). The lipid bilayer results from the self-association of the lipids hydrophobic moieties and the interaction of the hydrophilic moieties with aqueous environments. The same principle acts at the subcellular le ...
Deciphering the molecular functions of sterols in cellulose
Deciphering the molecular functions of sterols in cellulose

... requires a specific lipid environment. Consistent with this idea, its activity has been identified in detergent-resistant membranes (DRMs) that exhibit biochemical properties similar to sterol-rich PM microdomains (Bessueille et al., 2009). In the past 15 years, a model for the organization of the PM ...
Det här verket är upphovrättskyddat enligt Lagen (1960
Det här verket är upphovrättskyddat enligt Lagen (1960

... rides closest to the protein backbone are incorporated in the cisternae of the endoplasmic reticulum (22, 57) whereas more peripheral sugars are linked to the molecule in the Golgi area ...
Stockholm University
Stockholm University

... been recognized in several diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, and type II diabetes [16, 17]. In many cases, it has been demonstrated that the membrane may serve as a means for peptides to undergo structural rearrangements, which may be important for misfolding ev ...
Physiology of ionophore transport of potassium and sodium
Physiology of ionophore transport of potassium and sodium

... carbonyl oxygens coordinated to Na+ (av bond length 2.65Å) (Varma et al., 2008, 2011; Kholmurodov et al., 2010) which is similar to the crystal structure which has 3 bonds to the carbonyl oxygens and one water molecule hydrogen bonded to the Na+. There are several likely conformations of similar ene ...
Chloroplast structure: from chlorophyll granules to supra
Chloroplast structure: from chlorophyll granules to supra

... origins of the terms plastid, grana, stroma and chloroplasts to light microscopic studies of 19th century German botanists, and then describes how different types of electron microscopical techniques have added to this field. The most notable contributions of thin section electron microscopy include ...
Journal of Bacteriology
Journal of Bacteriology

... g. The pellet was washed with 80 ml of buffer A and resuspended in 16 ml of the same buffer. One volume of cell suspension was added to one volume of plastic beads (2% Styrol-DVB copolymer, 200 to 400 mesh, 40 to 80 A; Serva Entwicklungslabor, Heidelberg, Germany). The cells were disintegrated with ...
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Lipid bilayer



The lipid bilayer is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells. The cell membranes of almost all living organisms and many viruses are made of a lipid bilayer, as are the membranes surrounding the cell nucleus and other sub-cellular structures. The lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be. Lipid bilayers are ideally suited to this role because, even though they are only a few nanometers in width, they are impermeable to most water-soluble (hydrophilic) molecules. Bilayers are particularly impermeable to ions, which allows cells to regulate salt concentrations and pH by transporting ions across their membranes using proteins called ion pumps.Biological bilayers are usually composed of amphiphilic phospholipids that have a hydrophilic phosphate head and a hydrophobic tail consisting of two fatty acid chains. Phospholipids with certain head groups can alter the surface chemistry of a bilayer and can, for example, serve as signals as well as ""anchors"" for other molecules in the membranes of cells. Just like the heads, the tails of lipids can also affect membrane properties, for instance by determining the phase of the bilayer. The bilayer can adopt a solid gel phase state at lower temperatures but undergo phase transition to a fluid state at higher temperatures, and the chemical properties of the lipids' tails influence at which temperature this happens. The packing of lipids within the bilayer also affects its mechanical properties, including its resistance to stretching and bending. Many of these properties have been studied with the use of artificial ""model"" bilayers produced in a lab. Vesicles made by model bilayers have also been used clinically to deliver drugs.Biological membranes typically include several types of molecules other than phospholipids. A particularly important example in animal cells is cholesterol, which helps strengthen the bilayer and decrease its permeability. Cholesterol also helps regulate the activity of certain integral membrane proteins. Integral membrane proteins function when incorporated into a lipid bilayer, and they are held tightly to lipid bilayer with the help of an annular lipid shell. Because bilayers define the boundaries of the cell and its compartments, these membrane proteins are involved in many intra- and inter-cellular signaling processes. Certain kinds of membrane proteins are involved in the process of fusing two bilayers together. This fusion allows the joining of two distinct structures as in the fertilization of an egg by sperm or the entry of a virus into a cell. Because lipid bilayers are quite fragile and invisible in a traditional microscope, they are a challenge to study. Experiments on bilayers often require advanced techniques like electron microscopy and atomic force microscopy.
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