Lipids membrane Flashcards

Question

What is the role of NSF?

Answer 1

NSF (N-ethylmaleimide sensitive fusion factor) proteins disassemble the SNARE complex

Answer 2

1. Neurotransmitter-filled vesicle approaches plasma membrane. 2. When a local increase in [Ca2+] signals release of neurotransmitter, the v-SNARE, SNAP25, and t-SNARE interact, forming a coiled bundle of four helices, pulling the two membranes together and disrupting the bilayer locally. v-SNARE and t-SNARE bind to each other, zipping up from the amino termini and drawing the two membranes together. Zipping causes curvature and lateral tension on bilayers, favoring hemi-fusion between outer leaflets. 3. Hemi-fusion: outer leaflets of both membranes come into contact. 4. Complete fusion creates a fusion pore. 5. Pore widens; vesicle contents are released outside cell. Snare proteins are degraded and recycled

Answer 3

Happens against electrochemical gradient, driven by ion moving down its gradient

Answer 4

Down electrochemical gradient

Answer 5

Symport | Antiport

Answer 6

GLUTs are glucose transporters / solute transporters | Passive

Answer 7

Insulin signaling

Answer 8

Tissues where it is expressed: Erythrocytes and most tissues at a low level Role: Basal glucose uptake;

Answer 9

Tissues where it is expressed: Liver, pancreatic islets, intestine, kidney Role: In liver and kidney,

Answer 10

Tissues where it is expressed: Muscle, fat, heart Role: Activity increased by insulin

Answer 11

This cycle regulates the availability of the transporter at the cell membrane by regulating where the transporters are- inside the cytoplasm or at the cytoplasmic membrane By regulating the amount of the transporter present at the cell membrane, it regulates how much of glucose transporters are available for glucose transport The more transporters- the more glucose comes in as on the inside there's low concentration of glucose

Answer 12

1. Glucose transporters “stored” within cell in membrane vesicles. 2. When insulin interacts with its receptor, vesicles move to surface and fuse with the plasma membrane, increasing the number of glucose transporters in the plasma membrane. 3. When insulin level drops, glucose transporters are removed from the plasma membrane by endocytosis, forming small vesicles. 4. The smaller vesicles fuse with larger endosome. 5. Patches of the endosome enriched with glucose transporters bud of to become small vesicles, ready to return to the surface when insulin levels rise again

Answer 13

Outside of RBC there's a high concentration of CO2 which is excreted by cells into blood CO2 easily enters an erythrocyte, where it is converted to bicarbonate (HCO3- ) by the enzyme carbonic anhydrase. Now there's a high concentration of HCO3- which is excreted from RBC into blood plasma and then travels to the lungs In the lungs, HCO3- reenters the erythrocyte and is converted to CO2, which is eventually released into the lung space and exhaled. To be effective, this shuttle requires very rapid movement of HCO3- across the erythrocyte membrane.

Answer 14

Converts CO2 to HCO3-

Answer 15

The chloride-bicarbonate exchanger, also called the anion exchange (AE) protein, increases the rate of HCO3- transport across the erythrocyte membrane. This protein mediates the simultaneous movement of two anions: for each HCO3- ion that moves in one direction, one Cl- ion moves in the opposite direction, with no net transfer of charge; the exchange is electroneutral. This cotransport system allows the entry and exit of HCO3 without changing the membrane potential

Answer 16

The coupling of Cl and HCO3- movements is obligatory; in the absence of chloride, bicarbonate transport stops