Regulates the biosynthesis of dolichol phosphate-mannose . Regulatory subunit of the dolichol-phosphate mannose (DPM) synthase complex; essential for the ER localization and stable expression of DPM1 . Part of the glycosylphosphatidylinositol-N-acetylglucosaminyltransferase (GPI-GnT) complex that catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to phosphatidylinositol and participates in the first step of GPI biosynthesis . May act by regulating the GPI-GNT complex .
Subcellular locations: Endoplasmic reticulum membrane