Contributes to phosphatidylinositol N-acetylglucosaminyltransferase activity. Acts upstream of or within GPI anchor biosynthetic process. Part of glycosylphosphatidylinositol-N-acetylglucosaminyltransferase (GPI-GnT) complex. Is expressed in several structures, including alimentary system; genitourinary system; liver and biliary system; nervous system; and sensory organ. Human ortholog(s) of this gene implicated in developmental and epileptic encephalopathy 77. Orthologous to human PIGQ (phosphatidylinositol glycan anchor biosynthesis class Q). [provided by Alliance of Genome Resources, Apr 2022]