[8] Substituted-cysteine accessibility method

This chapter describes an approach to channels that combines chemical and genetic approaches and describes the synthesis and properties of some thiosulfonate derivatives, and it also describes applications of SCAM to ion channels, to transport proteins, and to the membrane-embedded binding sites of G-protein-coupled receptors.

Abstract

Publisher Summary The functional properties of ion channels, such as gating, ion selectivity, single-channel conductance, multi-ion occupancy, transient blocking, desensitization, and inactivation, have been extensively studied by eleclrophysiologic techniques. The molecular bases for these functions are being gradually revealed by protein chemical methods, by genetic manipulation, and by direct structural determinations. This chapter describes an approach to channels that combines chemical and genetic approaches. The substituted-cysteine accessibility method (SCAM) can be used to identify all of the residues that line a channel, to size the channel, to determine differences in the structures of the channel in different functional states, to locate the gates and selectivity filters, and to map the electrostatic potential profile in the channel. It describes the synthesis and properties of some thiosulfonate derivatives, and it also describes applications of SCAM to ion channels, to transport proteins, and to the membrane-embedded binding sites of G-protein-coupled receptors.