We have isolated a full-length cDNA specifying the muscle-specific subunit of human phosphoglycerate mutase (PGAM-M). The cDNA encodes a deduced protein 253 amino acids in length and contains an unusually short (37 nucleotides) 3'-untranslated region. The deduced human PGAM-M protein is clearly related to yeast PGAM and to human diphosphoglycerate mutase. Genomic Southern analysis using the PGAM-M cDNA as a probe implies the presence of a large PGAM gene family in the human genome, while Northern analysis demonstrates tissue-specific transcription of this isoenzyme gene.