Larger inhibition of visual pigment kinase in cones than in rods

J Neurochem. 2010 Oct;115(1):259-68. doi: 10.1111/j.1471-4159.2010.06925.x. Epub 2010 Aug 19.


In the carp retina, visual pigment kinase, GRK1 (G-protein coupled receptor kinase 1) in rods and GRK7 in cones, is inhibited by a photoreceptor neuronal Ca(2+)-sensor protein, S-modulin (or recoverin) in rods and visinin (formerly named s26) in cones. Here, we compared Ca(2+)-dependent inhibition of GRK1 by S-modulin and that of GRK7 by visinin. First, the concentrations of S-modulin and visinin in the outer segment were estimated: the concentration of visinin (1.2 mM) was 20 times higher than that of S-modulin (53 μM). Based on the determined concentrations of the Ca(2+)-sensor proteins and the known dark Ca(2+) concentrations, we estimated that in situ Ca(2+)-dependent inhibition on GRK in cones would be 2.5 times higher than that in rods at the Ca(2+) concentration in the dark. Because GRK activity is approximately 100 times higher in cones than in rods [Proc. Natl Acad. Sci. USA 102 (2005) 21359], the range of Ca(2+)-dependent inhibition on GRK activity is more than 100 times wider in cones than in rods. The inhibitory effects of S-modulin and visinin on photoreceptor GRKs were indistinguishable, although these Ca(2+)-sensor proteins are expressed in a cell-type specific manner. The inhibition by these Ca(2+)-sensor proteins was slightly higher on GRK7 than GRK1 probably because of a characteristic specific to GRK7.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Animals
  • Calcium / metabolism
  • Carps / metabolism*
  • Dose-Response Relationship, Drug
  • Fluorescent Antibody Technique
  • G-Protein-Coupled Receptor Kinase 1 / antagonists & inhibitors
  • Membranes / drug effects
  • Membranes / metabolism
  • Nerve Tissue Proteins / biosynthesis
  • Nerve Tissue Proteins / pharmacology
  • Nerve Tissue Proteins / physiology
  • Phosphorylation
  • Recoverin / biosynthesis
  • Recoverin / metabolism
  • Recoverin / pharmacology
  • Recoverin / physiology
  • Retinal Cone Photoreceptor Cells / enzymology*
  • Retinal Rod Photoreceptor Cells / enzymology*


  • Nerve Tissue Proteins
  • visinin
  • Recoverin
  • G-Protein-Coupled Receptor Kinase 1
  • Calcium