Mannosyl Oligosaccharide Glucosidase (MOGS)

Glucosidase I is the first enzyme in the N-linked oligosaccharide processing pathway. GCS1 cleaves the distal alpha-1,2-linked glucose residue from the Glc(3)-Man(9)-GlcNAc(2) oligosaccharide precursor. GCS1 is located in the lumen of the endoplasmic reticulum.GCS1 may also refer to "generative cell specific 1", also called HAP2 (hapless2), a gene of lower eukaryotes which is thought to be responsible for gametes fusion .

De Praeter et al. (2000) identified a glucosidase I defect in a neonate with severe generalized hypotonia and dysmorphic features consistent with congenital disorder of glycosylation type IIb (CDG2B). Molecular studies showed that the patient was a compound heterozygote for 2 missense mutations in the GCS1 gene.