Belonging to the glycosyltransferase 14 family, GCNT2 (glucosaminyl (N-acetyl) transferase 2, I-branching enzyme (I blood group)), also known as II, N-acetylglucosaminyltransferase, IGNT, CCAT, ULG3, GCNT5, GCNT2C or NACGT1, is a 400 amino acid glycosyltransferase that localizes to the Golgi apparatus. Other members of the glycosyltransferase 14 family include GCNT1, GCNT3, GCNT4, GCNT6 and GCNT7. A single-pass type II membrane protein, GCNT2 functions as a branching enzyme known as beta-1,6-N-acetylglucosaminyltransferase, which converts fetal i antigen to adult I antigen in erythrocytes during embryonic development. With expression levels increasing significantly during oncogenesis and development, GCNT2 is found at highest levels in adult prostate and fetal brain, and is found at low levels in heart, small intestine, colon, brain, pancreas and kidney.