Isolation of a cDNA encoding the B isozyme of human phosphoglycerate mutase (PGAM) and characterization of the PGAM gene family.

We previously reported the isolation of a full-length cDNA specifying the muscle-specific isozyme of human phosphoglycerate mutase (PGAM-M). We now report the isolation of a full-length cDNA specifying the non-muscle-specific, or brain (B), isozyme of human PGAM (PGAM-B). The PGAM-B cDNA encodes a deduced protein 254 amino acids long, 79% identical to PGAM-M, and contains a 913-nucleotide 3'-untranslated region, as compared to the unusually short 37-nucleotide 3'-untranslated region of PGAM-M. Northern analysis demonstrates the non-muscle-specific nature of PGAM-B transcription, while genomic Southern analysis implies the presence of a large PGAM family in the human genome. Most of the PGAM-hybridizing sequences in both the human and mouse genomes seem to be related to the B-isozyme gene; many members of the PGAM-B gene family in humans are apparently processed genes. These results agree with the evolutionary analysis, which indicates that the PGAM-B gene is the progenitor of the PGAM-M gene.