Endoplasmic reticulum α-1,2-mannosidase I (ERManI)

Endoplasmic reticulum α-1,2-mannosidase I (ERManI) is a type II transmembrane glycoside hydrolase enzyme that plays a critical role in the maturation and quality control of N-linked glycoproteins within the secretory pathway of eukaryotic cells. It is primarily responsible for trimming a single α-1,2-linked mannose residue from high-mannose oligosaccharides on nascent glycoproteins. This enzyme acts as a key regulator in protein quality control by generating degradation signals on misfolded glycoproteins, marking them for recognition and subsequent degradation via the ER-associated degradation (ERAD) pathway. While originally thought to reside exclusively in the ER, recent studies suggest a predominant localization in the Golgi complex, contributing to both protein folding quality control and retrograde transport mechanisms. Deficiency or dysfunction can disrupt normal protein homeostasis leading to accumulation of misfolded glycoproteins, potentially implicating it in certain congenital disorders of glycosylation (CDG).

Other names

ER mannosidase IMannosidase alpha class 1B member 1MAN1B1

Inhibition of α-1,2-mannose trimming from N-glycans