Electrical and Biochemical Properties of the cGMP-gated Cation Channel from Rod Photoreceptors

Abstract

The light-sensitive channel in the surface membrane of vertebrate photoreceptors is gated directly and cooperatively by cGMP, and the activation mechanism does not involve phosphorylation by a cGMP-dependent protein kinase. The channel protein most likely is composed of several copies of a single type of polypeptide, which can be removed from photoreceptor membranes by detergents and functionally reincorporated into the membrane of liposomes or planar bilayers. Most channel properties are preserved in the reconstituted system and provide a unique system to study the mechanisms of activation, regulation, and ion permeation in more detail.