Rhodopsin activation follows precoupling with transducin: inferences from computational analysis.
The electrostatic and shape complementarities between the crystal structures of dark rhodopsin and heterotrimeric transducin (Gt) have been evaluated by exhaustively sampling the roto-translational space of one protein with respect to the other. Structural complementarity, reliability, and consistency with in vitro evidence all converge in the same rhodopsin-Gt complex, showing that the functionally important R135 of the E/DRY motif is almost accessible to the C-terminus of Gt(alpha) already in the dark state. The main inference from this study is that activation of rhodopsin and Gt may be concurrent processes, consisting of conformational changes in a supramolecular complex formed prior to the light-induced activation of the photoreceptor.
Fanelli
Francesca
F
Department of Chemistry, University of Modena and Reggio Emilia, and Dulbecco Telethon Institute, via Campi 183 41100 Modena, Italy. fanelli@unimo.it
Dell'Orco
Daniele
D
D019295:Computational Biology; D003624:Darkness; D008958:Models, Molecular; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism; D055672:Static Electricity; D015293:Transducin / Q000737:chemistry* / Q000378:metabolism
D012243:Rhodopsin; D015293:Transducin