Molecular cloning of beta 3 subunit, a third form of the G protein beta-subunit polypeptide

Proc Natl Acad Sci U S A. 1990 Mar;87(6):2329-33. doi: 10.1073/pnas.87.6.2329.

Abstract

The signal-transducing guanine nucleotide-binding regulatory (G) proteins are heterotrimers composed of three subunits--alpha, beta, and gamma. Although multiple distinctive forms of the alpha subunit have been described, only two forms of the beta subunits of the G proteins have been identified. To investigate further the structural diversity of the beta subunits, we screened bovine and human retina cDNA libraries and isolated clones encoding three distinct types of G protein beta subunit. One form was identical to previously isolated beta 1-subunit cDNA clones that encode the 36-kDa form of the beta subunit, whereas a second form was identical to previously described beta 2 cDNAs that encode the 35-kDa beta isoform. In addition, we identified another species, designated beta 3 subunit, which encodes a third distinct form of the beta subunit. The beta 3-subunit cDNA corresponds to a 2.0-kilobase mRNA expressed in all tissues and clonal cell lines examined. Nucleotide sequence analysis indicates that the encoded peptide consists of 340-amino acid residues with a Mr of 37,221. The amino acid sequences of the three beta subunits are closely related: 83% identity between beta 1 and beta 3 subunits and 81% identity between beta 2 and beta 3 subunits. By contrast, the 3'-untranslated regions of the three cDNAs show no significant homology. Our data support the hypothesis that a family of beta-subunit polypeptides exists and extend understanding of beta-subunit structure.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cattle
  • Cloning, Molecular*
  • DNA / genetics
  • GTP-Binding Proteins / genetics*
  • Gene Library
  • Humans
  • Macromolecular Substances
  • Molecular Sequence Data
  • Nucleic Acid Hybridization
  • Oligonucleotide Probes
  • RNA, Messenger / genetics
  • Retina / metabolism
  • Sequence Homology, Nucleic Acid

Substances

  • Macromolecular Substances
  • Oligonucleotide Probes
  • RNA, Messenger
  • DNA
  • GTP-Binding Proteins

Associated data

  • GENBANK/M31328