Signaling (including calcium signaling)

Question 1

What does PDE5 do?

Answer 1

It breaks down cGMP into GMP and stops signal transduction.

Question 2

What advantage does Ca signaling have over others?

Answer 2

It is rapid. No synthesis required

Question 3

Give examples of sinks/sources of Ca

Answer 3

ER/SR, Nuclear Envelope, ECM, Mitochondria.

Question 4

What activates store-operated Ca Channels?

Answer 4

Low Ca in ER/SR

Question 5

Where is the only passive transporter that moves Ca into a sink?

Answer 5

The Ca uniporter in the mitochondria

Question 6

What are the functions of calcium buffers?

Answer 6

1. Restrict temporal and spatial spread of Ca++
2. Temporary storage of Ca

This is important because different Ca++ signals can cause different effects.

Question 7

What effect does Ca binding have on PKC?

Answer 7

It causes the C2 domain will associate with the plasma membrane

Question 8

How can calcium cause contraction and relaxation of smooth muscle?

Answer 8

Normal excitation causes RyR to release Ca++ and a global increase in Ca.

RyR can also cause local increases of Ca, which will hyperpolarize the nearby Ca-K channel, causing the closing of Ca voltage gated channels and thus relaxation.