BCHM 316 Chapter Notes - Chapter **31.1: Cyclic Adenosine Monophosphate

You decide to complete a summer undergraduate research project in a lab that studies G-Protein coupled receptor (GPCR) signaling. The laboratory you join has identified two new GPCRs, GPCR-A and GPCR-B. The same ligand binds each receptor, but two different heterotrimeric G-proteins are activated that regulate adenylyl cyclase. A. You find that activation of GPCR-A causes an increase in adenylyl cyclase activity, while activation of GPCR-B causes a decrease in adenylyl cyclase activity.

B. You have a cell line that expresses both GPCR-A, GPCR-B, the corresponding G proteins and adenylyl cyclase. There is a basal level of adenylyl cyclase activity that produces a baseline cAMP concentration. Your project is to characterize a series of mutations in these components. Will each mutation increase or decrease the intracellular levels of cAMP upon ligand addition (remember, both GPCR-A and GPCR-B bind the same ligand)?

a. A mutation in GPCR-A that prevents G-protein activation

b. A mutation in GPCR-B that prevents G protein activation

c. A mutation in Gsa that prevents release of bound GDP

d. A mutation in Gia that prevents GTP hydrolysis

EXPLAIN your thought process and why each one was answered as increase or decrease

1.) Protein kinases are involved in

A) the digestion of drugs to potentially toxic byproducts.

B) the degradation of enzymes to the component amino acids.

C) the phosphorylation of a wide variety of proteins.

D) the metabolism of drugs to water soluble compounds.

E) the cleavage of peptide bonds.

2.) Which of the following is triggered by the binding of glucose-6-phosphate to glycogen phosphorylase?

A) The protein changes from its T form to its R form.

B) The protein changes from its R form to its T form.

C) The protein becomes dephosphorylated.

D) It catalyzes the addition of a phosphate group to AMP.

E) It catalyzes the addition of a phosphate group to Ser-14.

3.) Which of the following amino acid residues are often involved in acid-base in enzyme-catalyzed reactions?

A) Histidine, aspartate, serine, and cysteine

B) Serine, tyrosine, arginine, and cysteine

C) Glutamine, asparagine, lysine, and tyrosine

D) Histidine, aspartate, lysine, and serine

E) Histidine, aspartate, glutamate, arginine, and lysine