Proteins in Motion

Abstract
Some membrane receptors undergo conformational changes after binding their ligand, generating a signal transduction cascade that results in a change in gene expression. But how the motion of proteins is translated into altered signaling is not known. In their Perspective, Gerstein and Chothia describe how transmembrane helices in a bacterial membrane receptor slide over each other in a piston-like motion ( Ottemann et al.). They discuss how these results fit with current models of transmembrane conformational changes and signaling and whether these findings are likely to be applicable to other types of transmembrane proteins.