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protein O-mannose kinase; POMK; protein kinase-like protein SgK196; sugen kinase 196 (POMK, SGK196)
Function:
- protein O-mannose kinase
- specifically mediates phosphorylation at the 6-position of an O-mannose of the trisaccharide (N-acetylgalactosamine (galNAc) -beta-1,3-N-acetylglucosamine (GlcNAc)-beta-1,4-mannose) to generate phosphorylated O-mannosyl trisaccharide (N-acetylgalactosamine-beta-1,3-N-acetylglucosamine-beta-1,4- (phosphate-6-)mannose)
- phosphorylated O-mannosyl trisaccharide is a carbohydrate structure present in alpha-dystroglycan (DAG1), which is required for binding laminin G-like domain-containing extracellular proteins with high affinity
- only shows kinase activity when the galNAc-beta-3-GlcNAc- beta-terminus is linked to the 4-position of O-mannose, suggesting that this disaccharide serves as the substrate recognition motif
ATP + N-acetyl-beta-D-galactosaminyl-(1->3)-N-acetyl-beta-D- glucosaminyl-(1->4)-O-alpha-D-mannosylprotein = ADP + N-acetyl-beta-D-galactosaminyl-(1->3)-N-acetyl-beta-D- glucosaminyl-(1->4)-O-alpha-D-(6-phospho)mannosylprotein
Kinetic parameters:
- KM=4.1 uM for ATP
Structure:
- belongs to the protein kinase superfamily, Ser/Thr protein kinase family, STKL subfamily
- contains 1 protein kinase domain
- although related to the Ser/Thr protein kinase family, has no protein kinase activity & acts as a mannose kinase instead [2]
Compartment:
- endoplasmic reticulum membrane
- single-pass type 2 membrane protein (probable)
Pathology:
- defects in POMK are associated with muscular dystrophy-dystroglycanopathy type A12
General
glycoprotein
membrane protein
protein kinase
Properties
SIZE: entity length = 350 aa
MW = 40 kD
COMPARTMENT: endoplasmic reticulum
MOTIF: transmembrane domain {21-43}
phosphorylation site
kinase domain
SITE: 81-350
MOTIF: ATP-binding site
NAME: ATP-binding site
N-glycosylation site {N165}
N-glycosylation site {N220}
N-glycosylation site {N235}
STATE: active state
Database Correlations
OMIM correlations
UniProt Q9H5K3
Pfam PF07714
Entrez Gene 84197
Kegg hsa:84197
References
- UniProt :accession Q9H5K3
- Yoshida-Moriguchi T, Willer T, Anderson ME et al
SGK196 is a glycosylation-specific O-mannose kinase
required for dystroglycan function.
Science. 2013 Aug 23;341(6148):896-9
PMID: 23929950