Kinase Family POMK
Kinase Classification: Group Other: Kinase Family POMK
POMK (Protein O-Mannose Kinase) is a poorly studied kinase, reported to phosphorylate O-mannose as part of protein glycosylation. It was originally published as SgK196 (Sugen Kinase 196).
Evolution
POMK is found in holozoans but it lost from several lineages, including insects and nematodes. It is a single copy gene in all vertebrates.
Domain Structure
The protein is composed mostly of an ePK kinase domain with a moderate N-term extension. No clear signal peptide or transmembrane region is seen, despite it's reported ER location. The kinase domain contains four highly conserved cysteine residues within the kinase domain, another two close to it's N-terminal border and a further conserved Cys just upstream. Similar to the RESK kinases, these conserved cysteines are unusual in kinases and may indicate presence in the Golgi or ER.
Function
POMK was found in a haploid genetic screen for defects in α-dystroglycan glycosylation [1]
[2]
[2]
Disease Association
Mutation of a conserved Q (Q258R) just after the APE motif and a conserved L (L137R) [1] were found in one patient with Walker-Warburg syndrome (WWS), a disease caused by failure to glycosylate α-dystroglycan.
and a stop mutation (Q109*) was found in a case of congenital muscular dystrophy (CMD), correlating with a lack of expression of α-dystroglycan protein [3]. A mouse knockout [4] showed hydrocephalus
References
- Jae pmid=23519211
- Yoshida-Moriguchi pmid=23929950
- vonRenesse pmid=24556084
- Vogel pmid=21746835
