title: Site of G protein binding to rhodopsin mapped with synthetic peptides from the alpha subunit.
abstract: The interaction between receptors and guanine nucleotide binding (G) proteins leads to G protein activation and subsequent regulation of effector enzymes. The molecular basis of receptor-G protein interaction has been examined by using the ability of the G protein from rods (transducin) to cause a conformational change in rhodopsin as an assay. Synthetic peptides corresponding to two regions near the carboxyl terminus of the G protein alpha subunit, Glu311-Val328 and Ile340-Phe350, compete with G protein for interaction with rhodopsin. Amino acid substitution studies show that Cys321 is required for this effect. Ile340-Phe350 and a modified peptide, acetyl-Glu311-Lys329-amide, mimic G protein effects on rhodopsin conformation, showing that these peptides bind to and stabilize the activated conformation of rhodopsin.
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001665:Binding Sites; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012168:Retinal Pigments / Q000378:metabolism*; D012243:Rhodopsin / Q000031:analogs & derivatives / Q000378:metabolism*; D015293:Transducin
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010455:Peptides; D012168:Retinal Pigments; C013110:metarhodopsins; D012243:Rhodopsin; D019204:GTP-Binding Proteins; D015293:Transducin