MAN1A1 encodes a class I mammalian Golgi 1,2-mannosidase which is a type II transmembrane protein. This protein catalyzes the removal of 3 distinct mannose residues from peptide-bound Man(9)-GlcNAc(2) oligosaccharides and belongs to family 47 of glycosyl hydrolases. Using an oligonucleotide probe derived from a pig liver Man(9)-mannosidase-specific cDNA template, Bause et al. (1993) isolated Man(9)-mannosidase from a human kidney cDNA library. The full-length cDNA predicted a 625-amino acid protein with a calculated molecular mass of 71 kD. Man(9)-mannosidase is a type II transmembrane protein with a short cytoplasmic polypeptide tail, a single transmembrane domain acting as a noncleavable signal sequence, a large luminal catalytic domain, and 3 potential N-glycosylation sites.