protein O-linked-mannose beta-1,2-N-acetylglucosaminyltransferase 1; POMGnT1; UDP-GlcNAc:alpha-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I.2; GnT I.2 (POMGNT1, MGAT12, UNQ746/PRO1475)

Function

• O-mannosyl glycosylation
• specific for alpha linked terminal mannose
• does not have MGAT3, MGAT4, MGAT5, MGAT7 or MGAT8 activity

UDP-N-acetyl-D-glucosamine + Man-R
            <-->
N-acetyl-D-glucosamine-beta-1,2-Man-R + UDP

Cofactor Mn+2

Kinetic parameters:

• KM=1.85 mM for mannosylpeptide
• KM=0.73 mM for UDP-GlcNAc
• KM=30 mM for man(alpha1-)O-benzyl
• KM=12 mM for CYA[man(alpha1-)O-T]AV pH dependence: optimum pH = 6.0

Structure

• amino acid residues between 299-311 are important for both protein expression & enzymatic activity
• minimal catalytic domain is located between positions 299-651
• single amino acid substitutions in the stem domain from muscle-eye-brain disease 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 role in the membrane-bound form
• belongs to the glycosyltransferase 13 family

Compartment

Golgi, Golgi membrane

Expression

constitutively expressed

Pathology

• defects in POMGNT1 associated muscle-eye-brain disease
• defects in POMGNT1 are a cause of Walker-Warburg syndrome

Laboratory

• POMGNT1 gene mutation

More general terms

• glycosyltransferase

Additional terms

• Fukuyama congenital muscular dystrophy (FCMD); Walker-Warburg syndrome FKTN-related

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=55624
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:55624
• OMIM: https://mirror.omim.org/entry/236670
• OMIM: https://mirror.omim.org/entry/253280
• OMIM: https://mirror.omim.org/entry/606822
• UniProt: http://www.uniprot.org/uniprot/Q8WZA1.html