title: Distinct forms of the beta subunit of GTP-binding regulatory proteins identified by molecular cloning.
abstract: Two distinct beta subunits of guanine nucleotide-binding regulatory proteins have been identified by cDNA cloning and are referred to as beta 1 and beta 2 subunits. The bovine transducin beta subunit (beta 1) has been cloned previously. We have now isolated and analyzed cDNA clones that encode the beta 2 subunit from bovine adrenal, bovine brain, and a human myeloid leukemia cell line, HL-60. The 340-residue Mr 37,329 beta 2 protein is 90% identical with beta 1 in predicted amino acid sequence, and it is also organized as a series of repetitive homologous segments. The major mRNA that encodes the bovine beta 2 subunit is 1.7 kilobases in length. It is expressed at lower levels than beta 1 subunit mRNA in all tissues examined. The beta 1 and beta 2 messages are expressed in cloned human cell lines. Hybridization of cDNA probes to bovine DNA showed that beta 1 and beta 2 are encoded by separate genes. The amino acid sequences for the bovine and human beta 2 subunit are identical, as are the amino acid sequences for the bovine and human beta 1 subunit. This evolutionary conservation suggests that the two beta subunits have different roles in the signal transduction process.
mesh_terms: D000311:Adrenal Glands / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics*; D005796:Genes; D006801:Humans; D046911:Macromolecular Substances; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D046911:Macromolecular Substances; D012333:RNA, Messenger; D004247:DNA; D019204:GTP-Binding Proteins