Phosphatidylinositol Glycan Q (PIGQ)

PIGQ is involved in the first step in glycosylphosphatidylinositol (GPI)-anchor biosynthesis. The GPI-anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. This gene encodes a N-acetylglucosaminyl transferase component that is part of the complex that catalyzes transfer of N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to phosphatidylinositol (PI). The full-length PIGQ cDNA encodes a deduced 581-amino acid protein that shares 24% overall amino acid identity with yeast Gpi1. The C-terminal half of PIGQ is better conserved than the N-terminal half. PIGQ has several hydrophobic regions, some of which may be transmembrane domains, and a potential tyrosine phosphorylation site in the third cytoplasmic loop.