Alpha-1,6-mannosyltransferase involved in glycosylphosphatidylinositol-anchor biosynthesis (By similarity). Transfers the second mannose to the glycosylphosphatidylinositol during GPI precursor assembly (By similarity). Required for maintenance of epithelial integrity during embryogenesis (PubMed:25807459). Glycolipid biosynthesis; glycosylphosphatidylinositol-anchor biosynthesis. Expressed in epithelial tissues including the epidermis, pharynx, intestine, rectum and excretory cell during embryogenesis. Belongs to the PIGV family.