#Question id: 1198
#Unit 4. Cell Communication and Cell Signaling
Both epinephrine and glucagon bind to G protein-coupled receptors and activate glycogen breakdown. Therefore, epinephrine and glucagon must:
#Question id: 1199
#Unit 4. Cell Communication and Cell Signaling
If you break liver cells by homogenization, separate the broken cell membranes (particulate) from the cytoplasm (soluble), and add epinephrine to the soluble portion, the result will be:
#Question id: 1200
#Unit 4. Cell Communication and Cell Signaling
Glucagon binds to the glucagon receptor, which interacts with a membrane-bound G protein, whose α subunit releases GDP and binds GTP. The α subunit then dissociates from the G protein and diffuses to a membrane-bound adenylyl cyclase which produces cAMP. In this scenario, name the
(1) transducer,
(2) effector,
(3) first messenger, and
(4) second messenger.
#Question id: 1201
#Unit 4. Cell Communication and Cell Signaling
Epinephrine binds to the same type of receptors in liver, fat, and smooth muscle cells. Yet in liver, glycogen breaks down; in fat, triacylglycerols break down; and smooth muscle cells relax. How can the same hormone produce three such different responses?
#Question id: 1202
#Unit 4. Cell Communication and Cell Signaling
G proteins are said to be self-inactivating. What G-protein function accounts for this?
#Question id: 1203
#Unit 4. Cell Communication and Cell Signaling
People who suffer from thyroid adenomas have constitutively activated G proteins in some cells of the thyroid gland. Tumor cells not only secrete copious quantities of thyroid hormones but also divide and grow excessively. Based on these observations, in what kind(s) of signal transduction pathways do the mutant G proteins participate?