Class I α-mannosidases (Glycoside hydrolase family 47) are involved in the trimming of mannose residues from the precursor oligosaccharide leading to the maturation of N-glycans. These enzymes recognize and cleave only α-1,2-linked mannose residues from the Man(9)GlcNAc(2) high-mannose precursor. This class is divided into three subfamilies depending on their cellular localization and biochemical properties. (Adapted from
FBrf0224862 and
PMID:17116466).