Recoverin mediates the calcium effect upon rhodopsin phosphorylation and cGMP hydrolysis in bovine retina rod cells.

Rhodopsin phosphorylation and in consequence cGMP hydrolysis in bovine rod outer segments are Ca2+ dependent in the presence of ATP. The level of rhodopsin phosphorylation decreases and the lifetime of active phosphodiesterase increases when the free [Ca2+] is raised from < 1 nM to about 1 microM; in both cases the half-maximal effect was observed at 140-170 nM of free Ca2+. Antibodies to recoverin reverse both effects at high [Ca2+] but have no influence at low [Ca2+]. We conclude that the Ca2+ effects observed are mediated by recoverin which inhibits rhodopsin kinase at a high Ca2+ level.