Reference rousselet a guthmann c matricon j bienvenue

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Reference: Rousselet A, Guthmann C, Matricon J, Bienvenue A & Devaux PF (1976) Study of the transverse diffusion of spin labeled phospholipids in bio- logical membranes: 1. Human red blood cells. Biochim. Biophys. Acta 426, 357–371. MEMBRANE PROTEINS DEFINITIONS 10–33 Lectin 10–34 Carbohydrate layer 10–35 Spectrin
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10–36 Multipass transmembrane protein 10–37 Bacteriorhodopsin 10–38 Cortex 10–39 Peripheral membrane protein 10–40 Glycosylphosphatidylinositol (GPI) anchor TRUE/FALSE 10–41 True. The lipid bilayer defines the structure of the membrane and provides a permeability barrier that separates the inside from the outside of the cell. Spe- cific membrane proteins allow particular solutes to enter and leave the cell, bind signaling molecules, and mediate attachment to the extracellular matrix. 10–42 False. While it is true that hydropathy plots are useful for identifying a -heli- cal transmembrane segments in proteins, they cannot identify transmem- brane b strands. a -Helical transmembrane segments can be reliably identi- fied because they involve 20–30 amino acids; transmembrane b strands are more difficult to identify because they involve only about 10 amino acids, which is insufficient to distinguish b strands in the interior of proteins from those that cross a membrane. 10–43 False. The carbohydrate on internal membranes is directed away from the cytosol toward the lumen of an internal membrane-enclosed compartment. Remember that the lumen of an internal compartment is topologically equivalent to the outside of the cell. 10–44 False. Human red blood cells contain no internal membranes at all; at an early stage in their development they extrude their nuclei. The lack of any internal membranes is the principal reason they have been used so exten- sively to investigate the structure of the plasma membrane. 10–45 True. The conformational changes that cause protons to be pumped are ini- tiated by a change in shape in the retinal chromophore upon absorption of a photon of light. 10–46 False. In addition to lipid rafts, which are microdomains with distinct lipid compositions, the apical and basolateral surfaces of epithelial cells, which are separated by intercellular tight junctions, also have different lipid com- positions. THOUGHT PROBLEMS 10–47 Thus far, arrangements A, B, D, E, F, and I have been found in biological membranes. Arrangement C, which has carbohydrate on the cytoplasmic side of the membrane, does not seem to exist. Arrangements G and H, which show proteins completely buried or with only their tips embedded in the membrane, have not been found and are thought unlikely to occur on theo- retical grounds. An arrangement similar to H, but with an amphiphilic a helix inserted horizontally into the cytoplasmic monolayer, has been found.
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