Gαq is the α subunit of one of the heterotrimeric GTP-binding proteins that mediates stimulation of phospholipase Cβ. We report the isolation and characterization of cDNA clones from a frontal cortex cDNA library encoding human Gαq. The encoded protein is 359 amino acids long and is identical in all but one amino acid residue to mouse Gαq. Analysis of human genomic DNA reveals an intronless sequence with strong homology to human Gαq cDNA. In comparison to Gαq cDNA, this genomic DNA sequence includes several small deletions and insertions that alter the reading frame, multiple single base changes, and a premature termination codon in the open reading frame, hallmarks of a processed pseudogene. Probes derived from human Gαq cDNA sequence map to both chromosomes 2 and 9 in high-stringency genomic blot analyses of DNA from a panel of human-rodent hybrid cell lines. PCR primers that selectively amplify the pseudogene sequence generate a product only when DNA containing human chromosome 2 is used as the template, indicating that the authentic Gαq gene (GNAQ) is located on chromosome 9. Regional localization by FISH analysis places GNAQ at 9q21 and the pseudogene at 2q14.3-q21.
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