Phosphatidylinositol Glycan C (PIGC)

PIGC encodes an endoplasmic reticulum associated protein that is involved in glycosylphosphatidylinositol (GPI) lipid anchor biosynthesis. The GPI lipid anchor is a glycolipid found on many blood cells and serves to anchor proteins to the cell surface. The encoded protein is one subunit of the GPI N-acetylglucosaminyl (GlcNAc) transferase that transfers GlcNAc to phosphatidylinositol (PI) on the cytoplasmic side of the endoplasmic reticulum. Two alternatively spliced transcripts that encode the same protein have been found for this gene. PIGC encodes a 297-amino acid polypeptide that is 20% identical to yeast GPI2. This gene, when transfected into human cells mutant for PIGC activity, restored proper GPI anchoring. Using immunolocalization, they found human PIGC protein to be present primarily in the ER in transfected cells.