Biology 2382B Lecture 10: Lecture 10

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lavenderimpala925

7 Jan 2019

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Lecture 10: functions of g-protein coupled receptors in cells. Activation of muscarinic acetylcholine receptor and k+ channels in the heart: when acetylcholine bind to its receptor, leads to opening of k+ channel and cellular hyperpolarisation. Slows the rate of heart muscle contraction: gbg subunit activates the effector protein (k+ channel) Regulation of adenylyl cyclase: adenylyl cyclase catalyzes formation of cyclic amp (camp) major secondary messenger, gpcr/camp pathway is very common in many mammalian cells. Two types of ligand receptor interactions and outcomes in this case. Cl- pumped out & na+ follows & h2o loss to intestine. In your lungs pertussis toxin toxin is secreted and gets inside of cells binding to g-alphai (inhibitory) subunit what it normally does is bind to and inhibit adenylyl cyclase so the toxin inhibits the inhibitor (causing activation) taking away the break away from adenylyl cyclase. Cellular responses to hormone-induced rise in camp in various tissues epinephrine.

Related Questions

Acetylcholine binds to a GPCR on heart muscle, making the heart beat more slowly. Remember, the activated receptor stimulates a G protein, which opens a K⁺ channel in the plasma membrane. Which of the following would enhance this effect of the acetylcholine?

(a) addition of a high concentration of a non-hydrolyzable analog of GTP

(b) addition of a drug that prevents the Î± subunit from exchanging GDP for GTP

(d) mutations in the acetylcholine receptor that weaken the interaction between the receptor and the G protein

7 A) Which of the following steps amplify the epinephrine signal response in cells?

1. receptor activation of G protein

2. G protein activation of adenylyl cyclase

3. cAMP activation of PKA

4. PKA phosphorylation of glycogen phosphorylase kinase (GPK)

2, 3, and 4

1, 3, and 4

1 and 3

1 and 4

7 B) Which of the following statements regarding ion channel regulation by GPCRs is FALSE?

Activation of GPCRs in rod cells leads to increased neurotransmitter release.

The muscarinic acetylcholine receptor activates a K+ channel via the G-beta/gamma subunit.

The G-alpha subunit is responsible for activation of PDE in the membrane of rod cells.

Activation of GPCRs in rod cells causes the closing of nonselective cation channels in the membrane.

harlequinhound34

Acetylcholine binds to a G-coupled protein receptor on the heart muscle to make the heart beat more slowly. It does so by stimulating the opening of K+ channels in the plasma membrane, which makes it more difficult to initiate and action potential. Describe the following on contraction of the heart.
A.) Addition of a drug that inhibits the GTPase activity of the Ga subunit.

B.) Mutations in the K+ channel that keep it closed all the tiem.

C.) A mutation that decreases the affinity of the (Beta gamma) complex of the G protein for the K+ channel.

greenelephant722

Biology 2382B Lecture 10: Lecture 10

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