C2006/F2402 '08 -- Extra Problem for Lecture 18
1. (Based on a question from Exam #2, '98) Suppose
protein kinase K has 2 regulatory subunits. Subunit A is calmodulin; subunit B is
phosphorylated by protein kinase A. (This example is made up, but there are enzymes like
this.)
A. PKK activity should be altered in response to changing levels of (cAMP) (DAG) (IP3) (cAMP & DAG) (cAMP & IP3) (IP3 & DAG) (all three) (none of these). Explain.
B. Suppose 2 different hormones activate PKK. Call them H1 and H2 (hormones 1 & 2). You get the following experimental results:
(1). Elevated levels of phosphodiesterase reduce the cellular response to H1 (but have no effect on response to H2).
(2). Antagonists of DAG have no effect on the response to either hormone.
(3). Inhibitors of phospholipase C inhibit the response to H2 (but have no effect on response to H1).
B-1. Given these results, H1 probably activates PKK using (adenylyl cyclase) (protein kinase C) (Ca++) (PKC and/or Ca++) (adenylyl cyclase and/or PKC) (adenylyl cyclase and/or Ca++) (any of these) (none of these), AND
B-2. H2 probably activates PKK using _____________________________________ , AND
B-3. H1 probably affects the state of (subunit A) (subunit B) (both) (neither) (can't predict), AND
B-4. H2 probably affects the state of _________________________________, AND
Outline the pathway of action of each hormone; show how effects of inhibitors etc. fit in.
C-1. G-proteins could be involved in the action of (H1) (H2) (both) (one or the other but not both) (neither) (can't predict).
C-2. A single G-protein could be involved in the action of _______________ (same choices as C-1).
C-3. A receptor that is a single pass protein could be involved in the action of ___________ (same choices as C-1).