The chromosomal locations of the genes for the common α subunit of the glycoprotein hormones and the Β subunit of chorionic gonadotropin in humans and mice have been determined by restriction enzyme analysis of DNA isolated from somatic cell hybrids. The CGα gene (CGA), detected as a 15-kb BamHI fragment in human DNA by hybridization to CGα cDNA, segregated with the chromosome 6 enzyme markers ME1 (malic enzyme, soluble) and SOD2 (superoxide dismutase, mitchondrial) and an intact chromosome 6 in human-rodent hybrids. Cell hybrids containing portions of chromosome 6 allowed the localization of CGA to the q12 → q21 region. The >30- and 6.5-kb BamHI CGB fragments hybridizing to human CGΒ cDNA segregated concordantly with the human chromosome 19 marker enzymes PEPD (peptidase D) and GPI (glucose phosphate isomerase) and a normal chromosome 19 in karyotyped hybrids. A KpnI-HindIII digest of cell hybrid DNAs indicated that the multiple copies of the CGΒ gene are all located on human chromosome 19. In the mouse, the α subunit gene, detected by a mouse thyrotropin (TSH) α subunit probe, and the CGΒ-like sequences (CGΒ-LHΒ), detected by the human CGΒ cDNA probe, are on chromosomes 4 and 7, respectively.
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