title: Alpha i-3 cDNA encodes the alpha subunit of Gk, the stimulatory G protein of receptor-regulated K+ channels.
abstract: cDNA cloning has identified the presence in the human genome of three genes encoding alpha subunits of pertussis toxin substrates, generically called "Gi." They are named alpha i-1, alpha i-2 and alpha i-3. However, none of these genes has been functionally identified with any of the alpha subunits of several possible G proteins, including pertussis toxin-sensitive Gp's, stimulatory to phospholipase C or A2, Gi, inhibitory to adenylyl cyclase, or Gk, stimulatory to a type of K+ channels. We now report the nucleotide sequence and the complete predicted amino acid sequence of human liver alpha i-3 and the partial amino acid sequence of proteolytic fragments of the alpha subunit of human erythrocyte Gk. The amino acid sequence of the proteolytic fragment is uniquely encoded by the cDNA of alpha i-3, thus identifying it as alpha k. The probable identity of alpha i-1 with alpha p and possible roles for alpha i-2, as well as additional roles for alpha i-1 and alpha i-3 (alpha k) are discussed.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D004247:DNA / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000235:genetics*; D005796:Genes; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D007473:Ion Channels; D046911:Macromolecular Substances; D004247:DNA; D019204:GTP-Binding Proteins; D011188:Potassium