Lodish Ch 15.1-2 TB MC

In paracrine signaling, the signaling molecule:

GTPases serve in many signal transduction pathways and the presence of GTP or GDP dictates whether the pathway is on or off, respectively. Which of the following statements is TRUE regarding guanine nucleotide exchange factors (GEF) and the role in these signaling pathways?

Cell sensitivity to an external signal is determined by:

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

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?

Of the components of a heterotrimeric G protein, which subunit(s) is(are) able to activate downstream responses?

In trimeric G proteins, GTP binds to:

Which of the following is NOT a common intracellular second messenger?

Phospholipase C is activated by:

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

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

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

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

CGMP phosphodiesterase catalyzes the conversion of:

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

Which of the following is a common step in the opening/closing of ion channels by acetylcholine and rhodopsin binding to their receptors?

Rhodopsin, a light-sensitive GPCR whose role in vision is dependent on its phosphorylation status, is influenced in part by the protein arrestin. Which of the following is TRUE with regard to rhodopsin and vision?

The G protein stimulated by light via the Rhodopsin receptor is ______ , while the effector is ______

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

Which of the following events occur during the epinephrine-stimulated conversion of glycogen to glucose-1-phosphate?

The activity of ẞ-adrenergic receptors is regulated by:

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:

Muscarinic acetylcholine receptors are GPCRs that slow the rate of heart muscle contraction upon ligand binding/activation. Activation of this receptor leads to opening of potassium channels triggered by decreases in cAMP levels. The muscarinic acetylcholine receptor likely couples to:

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?

Signal amplification is an important part of GPCR-mediated signaling. Which of the following steps do NOT directly amplify the signal?

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:

Which type of experimental evidence shows that the intrinsic GTPase activity of the Gα subunit is important for terminating effector activation?