EK Bio Typo?

[MedPR]

EK Bio Chapter 5 30 minute exam, Passage 1 problem 95, page 210.

The answer says "Gs protein does not activate adenylyl cyclase; it inhibits it, so B must be incorrect."

Shouldn't it say "Gi" protein does not activate...? Answer A is about Gs, Answer B is about Gi.

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[mcloaf]

Yes, that's a typo in the answer explanation. The answer that they explain (A), however, is still correct.

 

[chiddler]

What is a Gi protein? Not the same as G protein is it?

 

[MedPR]

What is a Gi protein? Not the same as G protein is it?

Gi is an inhibitory G-protein, Gs is a stimulatory G protein.

 

[mcloaf]

What is a Gi protein? Not the same as G protein is it?

Gs = G-stimulating

Gi = G-inhibiting

More or less exactly the same thing (subunit of a trimeric G-protein) but with opposite effect: inhibits rather than activates adenylyl cyclase. Some receptors have Gs, some have Gi.

 

[MedPR]

It's just another thing MCAT throws at you to see if you're paying attention.