Basic Biochem Kaplan 2

Question 1

Will insulin tend to phosphorylate or dephosphorylate enzymes?

Answer 1

dephosphorylate

Question 2

What are the main events in the cascade for NO action on vascular smooth muscle?

Answer 2

• NO diffuses into cell.
• activates GC -> up cGMP
• activates Protein kinase G
• smooth muscle relaxation

Question 3

Which NO prodrug works well on both arterioles and veins?

Answer 3

nitroprusside

Question 4

What is the risk of nitroprusside?

Answer 4

CN- toxicity. use only for a day or 2 in hypertensive crisis

Question 5

Which NO prodrug is used preferentially for htn and why?

Answer 5

Hydralazine - acts only on arterioles

Question 6

Which 2 NO prodrugs are preferable for angina? Why?

Answer 6

Nitrates: nitroglycerin and isosorbide dinitrate; preferentially dilate veins.

Question 7

What is the intracellular cascade that results from ANP binding to its receptor?

Answer 7

ANP receptor has intrinsic GC activity -> cGMP -> Protein kinase G

Question 8

What are the main effects of ANP?

Answer 8

Vascular smooth muscle relaxation; natriuresis; also inhibits cardiac hypertrophy and increases FFA release from adipocytes.

Question 9

What is the most common mutation in human cancers?

Answer 9

RAS

Question 10

How does insulin binding affect the insulin receptor?

Answer 10

Dimerization -> activation of Tyr kinase activity -> auto-phosphorylation (-> phosphorylation of SH2 proteins)

Question 11

What are the 3 main effects of SH2 proteins phosphorylation by the insulin receptor?

Answer 11

1. Phosphatase activation
2. p21-RAS activation -> growth
3. PI3 activation -> GLUT4 translocation to PM

Question 12

The p21-RAS enzyme has only 1 subunit. What is that subunit?

Answer 12

G-protein α subunit

Question 13

All growth factor receptors have _______ activity.

Answer 13

Tyrosine kinase

Question 14

What drug targets the Tyr kinase activity of bcr-abl in CML?

Answer 14

IMATINIB (Gleevec)

Question 15

For Pete’s sake, what kind of a receptor is the glucagon receptor?

Answer 15

Gs-coupled

Question 16

Is glycogen synthase active in the phosphorylated or dephosphorylated form?

Answer 16

DEphosphorylated

Question 17

Is glycogen phosphorylase active in the phosphorylated or dephosphorylated form? This is the RLS of what process?

Answer 17

phosphorylated - glycogenolysis

Question 18

Oncogenic mutations to p21-RAS cause what structural change?

Answer 18

Constantly bound to GTP -> constituitively active

Question 19

How do ETEC and cholera toxins cause watery diarrhea?

Answer 19

ADP-ribosylation of Gs proteins (activation) -> up cAMP ->->phosphorylation (activation) of CFTR

Question 20

What is the effect of pertussis toxin at the cellular level?

Answer 20

ADP-ribosylation of Gi-receptors (inactivation) –> up cAMP –> CFTR activation

Question 21

How do Pseudomonas and Diphtheria toxins prevent translocation in the ribosome?

Answer 21

ADP-ribosylation of eEF-2