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The human genome encodes at least three non‐allellic G proteins with α i ‐type subunits
Author(s) -
Suki Wadi N.,
Abramowitz Joel,
Mattera Rafael,
Codina Juan,
Birnbaumer Lutz
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80900-6
Subject(s) - complementary dna , biology , open reading frame , gene , protein subunit , microbiology and biotechnology , peptide sequence , rapid amplification of cdna ends , amino acid , genetics , molecular cloning
The amino acid sequence and composition of α‐subunits of signal transducing G proteins of the same kind appear to vary by no more than 2% from species to species. Here we isolated a human liver cDNA using an oligonucleotide complementary to the sequences encoding the pertussis toxin (PTX) ADP‐ribosylation site of the α‐subunit of the rat brain G protein called G i . Its open reading frame characterizes it as an α i ‐type cDNA—as opposed to α o ‐type—but predicts an amino acid composition that differs by 7% and 14%, respectively, from two other human α i ‐type molecules. Together with human brain α i (type‐1) and human monocyte α i (type‐2), the new human liver α i cDNA (type‐3) forms part of a family of α i molecules. Type‐3 α i cDNA hybridizes to a ∼ 3.6 kilobase long mRNA and type‐2 α i cDNA hybridizes to an mRNA species of ∼ 2.7 kilobases. This indicates that the human genome has at least three non‐allellic genes encoding non‐α o ‐type PTX substrates and provides structural evidence for the hypothesis that distinct effector systems are regulated by similar but nevertheless distinct PTX substrates.