title: Site-directed mutagenesis of highly conserved amino acids in the first cytoplasmic loop of Drosophila Rh1 opsin blocks rhodopsin synthesis in the nascent state.
abstract: The cytoplasmic surface of Drosophila melanogaster Rh1 rhodopsin (ninaE) harbours amino acids which are highly conserved among G-protein-coupled receptors. Site-directed mutations which cause Leu81Gln or Asn86Ile amino acid substitutions in the first cytoplasmic loop of the Rh1 opsin protein, are shown to block rhodopsin synthesis in the nascent, glycosylated state from which the mutant opsin is degraded rapidly. In mutants Leu81Gln and Asn86Ile, only 20-30% and <2% respectively, of functional rhodopsins are synthesized and transported to the photoreceptive membrane. Thus, conserved amino acids in opsin's cytoplasmic surface are a critical factor in the interaction of opsin with proteins of the rhodopsin processing machinery. Photoreceptor cells expressing mutant rhodopsins undergo age-dependent degeneration in a recessive manner.
authors.affiliation: Zoologisches Institut, Lehrstuhl 1, Universität Karlsruhe (T.H), Germany.
authors.forename: J
authors.initials: J
authors.lastname: Bentrop
authors.forename: K
authors.initials: K
authors.lastname: Schwab
authors.forename: W L
authors.initials: WL
authors.lastname: Pak
authors.forename: R
authors.initials: R
authors.lastname: Paulsen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics / Q000502:physiology*; D004596:Electroretinography; D005136:Eye Proteins / Q000737:chemistry* / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D008961:Models, Structural; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D011956:Receptors, Cell Surface / Q000737:chemistry*; D012160:Retina / Q000502:physiology*; D012243:Rhodopsin / Q000096:biosynthesis*; D017299:Rod Opsins / Q000096:biosynthesis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D029721:Drosophila Proteins; D005136:Eye Proteins; D011956:Receptors, Cell Surface; D017299:Rod Opsins; C083315:ninaE protein, Drosophila; D012243:Rhodopsin; D019204:GTP-Binding Proteins