RHODOPSIN PHOSPHORYLATION IN BOVINE ROD OUTER SEGMENTS IS MORE SENSITIVE TO THE INHIBITORY-ACTION OF RECOVERIN AT THE LOW RHODOPSIN BLEACHING THAN IT IS AT THE HIGH BLEACHING

Recoverin, a calcium-binding protein, is supposed to have rhodopsin ki nase as a target in the retinal rod cell, In the present work, we show that efficiency of recoverin as an inhibitor of rhodopsin phosphoryla tion in bovine rod outer segments is inversely proportional to the lev el of rhodopsin bleaching, These results, together with the data obtai ned previously in a reconstituted system (Senin et al, (1997) Biochem, J. 321, 551-555), allow us to hypothesize that recoverin might be res ponsible for a Ca2+-dependent regulation of the kinase in vivo, preven ting it from participating in the phosphorylation of unbleached rhodop sin. (C) 1997 Federation of European Biochemical Societies.