Question

1.Which of the following is a cell surface receptor? (selectany/all answers that apply)

	A.	Transducin
	B.	Ligand-gated ion channel
	C.	Receptor serine/threonine kinase
	D.	Steroid hormone receptor
	E.	Insulin receptor

2.Which of the following can act as anintracellular second messenger (select any/all answers thatapply)?

	A.	Sodium ions
	B.	Potassium ions
	C.	Calcium ions
	D.	Diacylglycerol
	E.	Inositol trisphosphate

3.GEFs:

	A.	is another term for GAPs.
	B.	accelerate the rate at which GBPs (GTP-binding proteins)hydrolyze their bound GTP.
	C.	accelerate the rate at which GBPs exchange GDP for GTP.
	D.	phosphorylate substrate molecules.
	E.	dephosphorylate substrate molecules.

4. Calmodulin binds calcium ions via:

	A.	leucine zipper motifs.
	B.	PH domains.
	C.	SH2 domains.
	D.	PTB domains.
	E.	EF hands.

5. Which of the following resides on theintracellular side of the plasma membrane (select any/allanswers that apply)?

	A.	the N-terminus of a GPCR
	B.	the C-terminus of a GPCR
	C.	the beta subunit of a heterotrimeric G protein
	D.	the G protein-binding domain of a GPCR
	E.	the ligand-binding domain of a GPCR

6. An activated GPCR typically functions as a(n) _____________for its associated heterotrimeric G protein.

	A.	GEF
	B.	GAP
	C.	RGS protein
	D.	kinase
	E.	phosphatase

7. GTP-binding to the alpha subunit of a heterotrimeric Gprotein causes (select any/all answers that apply):

	A.	the alpha subunit to dissociate from the beta/gamma dimer.
	B.	the beta subunit to dissociate from the gamma subunit.
	C.	all three G protein subunits to dissociate from one another.
	D.	the heterotrimeric G protein to dissociate from the GPCR.
	E.	the alpha subunit to dissociate from its effector molecule.

8. IP₃ receptors: (selectany/all answers that apply)

	A.	directly interact with PLC (Phospholipase C) at the plasmamembrane.
	B.	directly interact with PKC (Protein Kinase C) at the plasmamembrane.
	C.	are ligand-gated ion channels.
	D.	serve as a link between G?q activation and increasesin cytosolic calcium.
	E.	serve as a link between G?o activation and increasesin cytosolic calcium.

9. CaM kinases: (select any/all answersthat apply)

	A.	are activated by calcium/calmodulin complexes.
	B.	are tyrosine kinases.
	C.	are serine/threonine kinases.
	D.	have a structure similar to PKA.
	E.	have a structure similar to PKC.

10. The primary or most proximate event that accounts forlight-induced hyperpolarization of photoreceptors is:

	A.	the gating of ion channels by retinal.
	B.	a rapid fall in the concentration of cGMP, leading to closure ofNa+/Ca2+channels.
	C.	a rapid rise in the concentration of cGMP, leading to closure ofNa+/Ca2+channels.
	D.	a sudden increase in the concentration of cAMP, leading toactivation of potassium channels.
	E.	light-induced photoisomerization of calcium channels.

11. A man with a genetic mutation expresses a defective form ofthe cation channel responsible for the