Exam 14: Signal Transduction and G-Protein Coupled Receptors

Pull-down assays can be used to detect when small G proteins like Rac1 have been activated by various growth factors.If you were given two lysates,one having been treated with platelet-derived growth factor (PDGF)and the other treated with PDGF that had been heat-inactivated,briefly describe the pull-down assay and what you would expect to see following the assay.

Which of the following general statement(s)about a G protein-coupled receptor is (are)TRUE?

Explain the differences between endocrine,paracrine,and autocrine signaling.

If [R] = the free receptor concentration and [L] = the free ligand concentration,Kd is:

Cholera toxin can make you sick through overactivation of a Gαs pathway even if your body stops making the ligand associated with activation of the pathway.Knowing this,which of the following CANNOT be true about cholera toxin?

All the following statement(s)about cholera toxin are TRUE,except:

cGMP phosphodiesterase catalyzes the conversion of:

One form of receptor desensitization can be mediated by negative feedback involving phosphorylation of the receptor itself by a kinase activated downstream of a second messenger.The phosphorylated receptor likely:

Cell sensitivity to an external signal is determined by:

Pull-down assays using proteins that ONLY bind to the GTP-bound version of the small G-protein can be used to detect when small G proteins like Rac1 have been activated by various growth factors.You were given two lysates,one having been treated with platelet-derived growth factor (PDGF)and the other not treated with PDGF.This method is similar to performing co-IPs,so based on that knowledge,which of the following steps is erroneous?

β-blockers inhibit an adrenergic receptor found on many cell types in the body,including heart cells.Patients who have arrhythmias (irregular heartbeats)most likely benefit from what downstream action of these drugs?

1,2-diacylglycerol (DAG)and inositol 1,4,5-trisphosphate (IP3)are cleaved from phosphatidylinositol 4,5-bisphosphate (PIP₂)by the enzyme:

How does the body respond to decreases in blood glucose levels below about 5 mM?

Describe the steps in the synthesis of 1,2-diacylglycerol (DAG)and inositol 1,4,5-trisphosphate (IP₃)from phosphatidylinositol (PI).

Which of the following statements about adenylyl cyclase stimulation/inhibition in adipose cells is TRUE?

Phosphatidylinositol 4,5-bisphosphate (PIP₂)is cleaved by phospholipase C into:

Which enzyme plays a role in regulating rhodopsin-induced closing of cation channels?

Which of the following mechanisms can terminate an intracellular signaling pathway once the concentration of an external signal decreases?

When the regulatory domain of PKA is bound to cAMP:

Summarize the steps in the cycling of GTPase switch proteins from active to inactive states.