Endoplasmic reticulum Class I α-mannosidases are involved in the cleavage of a single mannose residue in the middle branch of Man(9)GlcNAc(2) to produce a unique Man(8)GlcNAc(2) isomer. They mediate quality control in the ER by creating specific glycoform that is recognized by EDEM (ER degradation-enhancing α-mannosidase-like protein), a putative degradation family of lectins. (Adapted from
PMID:17116466).
