Why does rhodopsin have an unusually stable structure for a GPCR?
A)Its ligand is permanently bound to the protein.
B)A retinal group is permanently bound to the protein.
C)The protein molecule can only exist in a single conformation in the absence of a stimulus.
D)The protein molecule can only exist in a single conformation in the dark.
E)All of these are correct.

Question

Quizplus · Accepted Answer

Rhodopsin, a GPCR involved in vision, has an unusually stable structure because it has a retinal group permanently bound to it (B), which essentially acts as its ligand (A). This binding stabilizes the protein in a specific conformation in the absence of light (D), and it is generally considered that in the dark (or absence of a stimulus), rhodopsin exists in a stable, inactive conformation (C). Thus, all the provided reasons contribute to the unusual stability of rhodopsin's structure.

Why Does Rhodopsin Have an Unusually Stable Structure for a GPCR