This is a family of two different beta-1,6-N-acetylglucosaminyltransferase enzymes, I-branching enzyme (eg Swiss:Q06430) and core-2 branching enzyme (eg Swiss:Q02742). I-branching enzyme is responsible for the production of the blood group I-antigen during embryonic development [1]. Core-2 branching enzyme forms crucial side-chain branches in O-glycans [2]. This is a fmmily of glycosyl-transferases that are Type II membrane proteins that are found in the endoplasmic reticulum (ER) and Golgi apparatus [2].

1: Expression of the developmental I antigen by a cloned human cDNA encoding a member of a beta-1,6-N-acetylglucosaminyltransferase gene family. Bierhuizen MF, Mattei MG, Fukuda M; Genes Dev 1993;7:468-478. PMID:8449405

2: Molecular cloning and expression of a novel beta-1, 6-N-acetylglucosaminyltransferase that forms core 2, core 4, and I branches. Yeh JC, Ong E, Fukuda M; J Biol Chem 1999;274:3215-3221. PMID:9915862

3: Plant Glycosyltransferases Beyond CAZy: A Perspective on DUF Families. Hansen SF, Harholt J, Oikawa A, Scheller HV; Front Plant Sci. 2012;3:59. PMID:22629278