Probing Rhodopsin−Transducin Interactions by Surface Modification and Mass Spectrometry

Publisher Website
Google Scholar
Abstract
The interactions of rhodopsin and the α-subunit of transducin (Gt) have been mapped using a surface modification “footprinting” approach in conjunction with mass spectrometric analysis employing a synthetic peptide corresponding to C-terminal residues 340−350 of the α-subunit of Gt, Gtα(340−350). Membrane preparations of unactivated (Rh) and light-activated rhodopsin (Rh*), each in the presence or absence of Gtα(340−350), were acetylated with the water-soluble reagent sulfosuccinimidyl acetate, and the extent of the acetylation was determined by mass spectrometry. By comparing the differences in acetylation among Rh, Rh*, and the Rh−Gtα(340−350) and Rh*−Gtα(340−350) complexes, we demonstrate that the surface exposure of the acetylation sites was reduced by the conformational change associated with light activation, and that binding of Gtα(340−350) blocks acetylation sites on cytoplasmic loops 1, 2, and 4 of Rh*. In addition, we show evidence of interaction between the end of the C-terminal tail of rhodopsin and Gtα in the unactivated state of rhodopsin.

This publication has 0 references indexed in Scilit: