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13 Cards in this Set
- Front
- Back
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what are the lipid components of membranes |
1. phosphoglycerides 2. sphingolipids (sphingomyelin) 3. glycolipids 4. sterols (cholesterol) |
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what does cholesterol do in the membrane |
gives stability, increase rigidity without altering fluidity broadens temperature transition phase of membranes |
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what is the purpose of inner and outer membrane flipping |
lipids changing signal cell death apoptosis |
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describe glycolipids |
only in plasma membrane in outer leaflet cell recognition, immunity etc. |
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describe peripheral membrane proteins |
interact with charged surface of bilayer or interact with integral proteins in the bilayer |
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describe integral proteins |
part of protein interacts directly with bilayer two main types: alpha helices beta barrels |
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what are the major functions of membrane proteins |
1. recognition/identification (glycophorin, beta adrenergic receptor, insulin receptor) 2. transport (glucose transport, anion transport) 3. structure and organization (spectrin, ankyrin) 4. signal transduction (g proteins, adenylyl cyclase, phospholipase C) |
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describe glycophorin |
ubiquitously expressed integral membrane protein presenter of antigenic carbohydrate sequences single pass long external and cytoplasmic domains |
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describe the glucose transporter |
GLUT1 mutliple passes polar/charged amino acids form inside of channel |
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describe the Band 3 anion channel |
integral membrane protein crosses 14 times exchanges chloride for bicarbonate maintains homeostasis RBCs: bohr effect-- CO2 to bicarbonate so OxyHb releases O2 remove acidic buildup of bicarbonate, maintain membrane potential with Cl- exchange |
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describe spectrins |
long filamentous peripheral membrane protein major cytoskeleton component |
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describe the erythrocyte cytoskeleton |
interactions between filamentous proteins (spectrin/actin) and integral membrane proteins (glycophorin and band 3) mediated by anchoring proteins (ankyrin and protein 4.1) |
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what is the significance of the cytoskeleton |
1. maintenance of cellular shape: biconcave shape of RBC preserved under extreme sheer forces in capillaries, preserve high SA 2. distribution of integral membrane proteins transporters and receptors maintained, assisting their functions |
