title: The gamma-subunit of the principal G-protein from squid (Loligo forbesi) photoreceptors contains a novel N-terminal sequence.
abstract: The squid (Loligo forbesi) visual system presents as accessible a system for study of G-protein mediated signal transduction as the vertebrate rod outer segment with the added advantage that the major G-protein is a member of the Gq-class. Here the cDNA clone encoding the gamma-subunit of this G-protein is reported, thereby completing the molecular cloning of the heterotrimeric G-protein. The deduced protein structure of G-gamma has relatively little sequence identity with known mammalian counterparts particularly in comparison with the relatively high degree found for both the alpha- and beta-subunits of this protein. In particular, the N-terminus of the squid visual G-gamma contains a repetitive, highly charged region, rich in lysine and glutamate, that has no parallel in other G-proteins. The amino acid sequence of a number of peptides derived by chemical cleavage of G-gamma accounted for much of the protein sequence predicted from the cDNA, including the unusual N-terminal region.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Leeds, UK.
authors.forename: J S
authors.initials: JS
authors.lastname: Lott
authors.forename: N J
authors.initials: NJ
authors.lastname: Ryba
authors.forename: J D
authors.initials: JD
authors.lastname: Pottinger
authors.forename: J N
authors.initials: JN
authors.lastname: Keen
authors.forename: A
authors.initials: A
authors.lastname: Carne
authors.forename: J B
authors.initials: JB
authors.lastname: Findlay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D004247:DNA; D049832:Decapodiformes; D019204:GTP-Binding Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
chemical_list: D004247:DNA; D019204:GTP-Binding Proteins