GRK7/GPRK7

GRK7 is the least studied vertebrate member of the GRK family and the cone-specific counterpart of GRK1 in the visual subfamily. It is expressed in cone photoreceptors and, in model organisms such as zebrafish, carries out phosphorylation of cone opsins that terminates cone phototransduction together with cone arrestin. Structurally it retains the subfamily kinase core and the N-terminal acylation site that anchors visual GRKs to outer-segment membranes, whereas GRK7 expression in human tissue is far lower than that of GRK1. Recombinant GRK7 is a tool for comparative opsin-kinase biochemistry, arrestin-recruitment assays and studies of calcium-dependent modulation of visual GRK activity.