Cell Bio: Plasma Membrane Flashcards Preview

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Flashcards in Cell Bio: Plasma Membrane Deck (15):
1

3 main receptor types; which is intracell?

1. Receptor tyrosine kinase
2. G- protein coupled receptor
3. Steroid receptor (intracell in cytosol)

2

Which RTK (receptor tyrosine kinase) have single pass transmembrane protein? (1)

PDGF

3

Which two RTK have 4 subunits? Which portion is extracellular?

Insulin and IGF-1 receptors--> 2 alpha are bound by disulfide bonds and bind extracell ligand; 2 beta subunits are intracell and have tyrosine kinase activity

4

What is the first step in activity of RTKs?

autophosphorylation

5

What protein on clathrin do the receptor proteins (the ones that extend extracellulary) bind to?

adaptin

6

What protein helps to pinch off a vesicle in reeptor-mediated endocytosis?

dynamin

7

What happens to LDL receptors once they are endocytoses with the help of clathrin?

1. Clathrin uncoats from vesicle
2. contents delivered to lysosome
3. Portion of endosome with LDL receptor buds off an RETURNS TO PLASMA MEMBRANE

8

What is defective in a mutant LDL receptor that causes familial hypercholesterolemia?

cant bind to adaptin--> LDL receptor works fine, but cannot do endocytosis, b/c cant bind to clathrin

9

Kinases and phospharylases are different how?

Kinase--> phosphorylate using ATP
Phosphorylase--> phoshphorylates using inorganic phosphate in an ATP-independent fashion

10

What enzyme removes phosphate groups?

Phosphatate

11

What cofactor do carboxylases need?

Biotin--> these add a carbon group

12

What does Na+/K+ ATPase do?

puts 3 Na+ out of the cell in exchange for 2 K+ coming in

13

What are drugs that inhibit Na+/K+ ATPase? Why useful in heart dz?

Cardiac glycosides (digoxin and digitoxin)--> inhibit the Na+/K+ ATPase directly. Increased Na+ in the cell decreases the activity of a Na+/Ca++ exchanger that pumps Ca out of the cell--> increased Ca++ = increased myocardial contractility

14

Two most abundant substances in plasma membrane

1. proteins
2. phospholipids

15

How does ouabain inhibit Na/K ATPase?

binds to K+ binding site

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