Figure 7: Model of different binding modes of arrestin.
From: Distinct loops in arrestin differentially regulate ligand binding within the GPCR opsin
(a) Crystal structure of Meta II (M II) (PDB code 3PXO). (b) Rhodopsin (Rho) (1U19), which is similar to inactive opsin in conformation30. (c) Arrestin with closed conformation of loop-72 (molecule D from 1CF1). (d) Arrestin with extended conformation of loop-72 (molecule A from 1CF1). The N-domain is coloured blue, the C-domain is coloured green and the C-terminus has been omitted for clarity. Sites labelled in this study are indicated. (e) As described in the text, arrestin binds light-induced Meta II-P in 1:1 or 1:2 complexes. (f) Arrestin binds functional dimers of OpsP, in which agonist (ATR) can enter one protomer and thereby reform Meta II-P. Meta II-P decay results in an equilibrium of free and bound ATR.
