Substitution of cysteic acid for the seven phosphorylated residues in bovine rhodopsin C-terminal peptide

We have previously synthesized peptide 330-348 from the carboxyl terminal region of bovine rhodopsin containing 4 pThr and 3 pSer residues [1]. This peptide activated arrestin, causing arrestin to bind to non-phosphorylated, light-activated rhodopsin (R*) [2] and inhibited the light-induced phosphodiesterase (PDE) activity in rod outer segments [3]. We have synthesized a new analog substituting cysteic acid for all of the phosphorylated residues, DDEAXXXVXKXEXXQVAPA where X = cysteic acid (7 Cya peptide), to test whether cysteic acid would substitute for the phosphorylated residues and activate arrestin.