Cross-Linking of Transmembrane Helices Reveals a Rigid-Body Mechanism in Bacteriorhodopsin Transport

摘要

In membrane proteins, the mechanisms driving transmembrane (TM) helices through the conformational changes needed to accomplish the translocation of substrates or for intraprotein signal transduction are still a matter of debate. Do the helices follow an alternating mechanical rocker-switch mechanism or do they act as soft structures, which would allow a Brownian ratchet mechanism? Are the interruptions or the hinges in the middle of transmembrane helices necessary to allow individual movements of parts of the helices?