Cysteine-based cross-linking approach to study inter-domain interactions in ion channels.

Cysteine contains a highly reactive thiol group and therefore under oxidizing conditions a disulfide bond can form between a pair of cysteines that are juxtaposed in the close vicinity, which can be only reversed by reducing agents. These attributes have been elegantly exploited to study the functional role of an interaction or contact between two adjacent domains that are present in ion channels or virtually in any proteins, by introducing double cysteine substitutions at the domain interface and measuring changes in the ion channel functions arising from cross-linking the two substituted cysteines via formation of a disulfide bond. Here I describe this cysteine-based cross-linking approach.