G alpha 12 and G alpha 13 subunits define a fourth class of G protein alpha subunits

Proc Natl Acad Sci U S A. 1991 Jul 1;88(13):5582-6. doi: 10.1073/pnas.88.13.5582.


Heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) are central to the signaling processes of multicellular organisms. We have explored the diversity of the G protein subunits in mammals and found evidence for a large family of genes that encode the alpha subunits. Amino acid sequence comparisons show that the different alpha subunits fall into at least three classes. These classes have been conserved in animals separated by considerable evolutionary distances; they are present in mammals, Drosophila, and nematodes. We have now obtained cDNA clones encoding two murine alpha subunits, G alpha 12 and G alpha 13, that define a fourth class. The translation products are predicted to have molecular masses of 44 kDa and to be insensitive to ADP-ribosylation by pertussis toxin. They share 67% amino acid sequence identity with each other and less than 45% identity with other alpha subunits. Their transcripts can be detected in every tissue examined, although the relative levels of the G alpha 13 message appear somewhat variable.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • DNA / genetics
  • GTP-Binding Protein alpha Subunits, G12-G13
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / classification*
  • GTP-Binding Proteins / genetics
  • Mice
  • Molecular Sequence Data
  • Oligonucleotides / chemistry
  • Polymerase Chain Reaction
  • RNA, Messenger / genetics


  • Oligonucleotides
  • RNA, Messenger
  • DNA
  • GTP-Binding Proteins
  • GTP-Binding Protein alpha Subunits, G12-G13

Associated data

  • GENBANK/M55515
  • GENBANK/M59224
  • GENBANK/M59225
  • GENBANK/M59226
  • GENBANK/M60611
  • GENBANK/M63659
  • GENBANK/M63660
  • GENBANK/M64651
  • GENBANK/M64652
  • GENBANK/M64653