Effects of phosphorylation on the structure of the G-protein receptor rhodopsin

Upon activation by light, rhodopsin is subject to phosphorylation by rhodop sin kinase at serine and threonine residues in the carboxyl terminal region of the protein. A 19 amino acid peptide that corresponds to the carboxyl t erminal end of rhodopsin (residues 330-348) and contains these phosphorylat ion sites was synthesized. The structure of this peptide was determined usi ng two-dimensional proton NMR. The structure of this peptide was similar to that determined for this region in peptides corresponding to the carboxyl 33 and 43 amino acids of rhodopsin. The effect of phosphorylation on the st ructure of the carboxyl terminal domain of rhodopsin was determined by solv ing the solution structures of the peptide containing residues 330-348 with phosphorylation at one (residue 343), three (residues 343, 338, and 334) a nd seven residues (residues 334, 335, 336, 338, 340, 342, 343). These data indicate that the major structural change occurs upon phosphorylation of th e first residue, and that an additional structural change occurs with seven phosphates. (C) 1999 Published by Elsevier Science B.V. All rights reserve d.