Catalytic activity:UDP-N-acetyl-D-glucosamine + Man-R = N-acetyl-D-glucosamine-beta-1,2-Man-R + UDP.,cofactor:Manganese.,Disease:Defects in POMGNT1 are a cause of Walker-Warburg syndrome (WWS) [MIM:236670]; also known as hydrocephalus-agyria-retinal dysplasia or HARD syndrome. WWS is an autosomal recessive disorder characterized by cobblestone lissencephaly, hydrocephalus, agyria, retinal displasia, with or without encephalocele. It is often associated with congenital muscular dystrophy and usually lethal within the first few months of life.,Disease:Defects in POMGNT1 are the cause of muscle-eye-brain disease (MEB) [MIM:253280]. MEB is an autosomal recessive disorder characterized by congenital muscular dystrophy, ocular abnormalities, cobblestone lissencephaly and cerebellar hypoplasia. MEB patients present severe congenital myopia, congenital glaucoma, pallor of the optic disks, retinal hypoplasia, mental retardation, hydrocephalus, abnormal electroencephalograms, generalized muscle weakness and myoclonic jerks.,Domain:Amino acid residues between 299-311 are important for both protein expression and enzymatic activity. The minimal catalytic domain is located between positions 299-651. Single amino acid substitutions in the stem domain from MEB patients abolished the activity of the membrane-bound form but not the soluble form. This suggests that the stem domain of the soluble form is unnecessary for activity, but that some amino acids play a crucial role in the membrane-bound form.,Function:Participates in O-mannosyl glycosylation. May be responsible for the synthesis of the GlcNAc(beta1-2)Man(alpha1-)O-Ser/Thr moiety on alpha-dystroglycan and other O-mannosylated proteins. Is specific for alpha linked terminal mannose and does not have MGAT3, MGAT4, MGAT5, MGAT7 or MGAT8 activity.,online information:GlycoGene database,online information:Protein O-linked-mannose beta-1,2-N-acetylglucosaminyltransferase 1,pathway:Protein modification; protein glycosylation.,similarity:Belongs to the glycosyltransferase 13 family.,tissue specificity:Constitutively expressed. An additional weaker band is also detected in spinal cord, lymph node, and trachea. Expressed especially in astrocytes. Also expressed in immature and mature neurons.,
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