Molecular cloning of human g alpha(q) cDNA and chromosomal localization of the g alpha(q) gene (GNAQ) and a processed pseudogene

G alpha(q) is the alpha subunit of one of the heterotrimeric GTP-binding proteins that mediates stimulation of phospholipase C beta. We report the isolation and characterization of cDNA clones from a frontal cortex cDNA library encoding human G alpha(q) The encoded protein is 359 amino acids long and is identical in all but one amino acid residue to mouse G alpha(q). Analysis of human genomic DNA reveals an intronless sequence with strong homology to human G alpha(q) cDNA. In comparison to G alpha(q) 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 G alpha(q) 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 G alpha(q) gene (GNAQ) is located on chromosome 9. Regional localization by FISH analysis places GNAQ at 9q21 and the pseudogene at 2q14.3-q21.