Protein O-mannose kinase (Pomk)

Protein O-mannose kinase that specifically mediates phosphorylation in the 6-position of an O-mannose of the trisaccharide (N-acetylgalactosamine (GalNAc)-beta-1,3-N- acetylglucosamine (GlcNAc)-beta-1,4-mannose) to create 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 needed for binding laminin G-like domain-containing extracellular proteins with high affinity.

Only shows kinase activity once the GalNAc-beta-3-GlcNAc-beta-terminus is associated with the 4-position of O-mannose, suggesting that this disaccharide serves as the substrate recognition motif (By similarity). .