Dolichol Kinase (DOLK)

Dolichyl monophosphate is an essential glycosyl carrier lipid for C- and O-mannosylation and N-glycosylation of proteins and for biosynthesis of glycosyl phosphatidylinositol anchors in endoplasmic reticulum (ER). Dolichol kinase, or TMEM15, catalyzes CTP-mediated phosphorylation of dolichol, the terminal step in de novo dolichyl monophosphate biosynthesis. the 538-amino acid DK1 protein has a predicted molecular mass of 59.3 kD. It has 13 transmembrane (TM) domains and shares 30% amino acid identity with yeast Sec59. DK1 expressed in insect cells had an apparent molecular mass of 59 to 60 kD by SDS-PAGE.Overexpression of DK1 in Sec59-deficient yeast increased the cellular pool of dolichol phosphate. Crude microsomes from DK1-transfected insect cells showed a 15-fold increase in DK activity compared with controls.