polypeptide N-acetylgalactosaminyltransferase-like protein 2

^[1]^[2]

Function

glycosylation
catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, transfer of an N-acetyl-D-galactosamine residue to a Ser or Thr on the protein
much weaker activity toward all substrates tested compared to GALNT2, but able to transfer up to 7 GalNAc residues to Muc5AC peptide
prefers Muc1a as substrate

UDP-N-acetyl-D-galactosamine + polypeptide
                    <-->
UDP + N-acetyl-D-galactosaminyl-polypeptide

Cofactors: Mn+2, Ca+2

2 conserved domains in the glycosyltransferase region
- N-terminal domain (domain A, also called GT1 motif), involved in Mn+2 coordination & substrate binding
- C-terminal domain (domain B, also called Gal/GalNAc-T motif) involved in catalysis & UDP-Gal binding
ricin B-type lectin domain binds to GalNAc & contributes to glycopeptide specificity
belongs to the glycosyltransferase 2 family, GalNAc-T subfamily.
contains 1 ricin B-type lectin domain

Golgi membrane

widely expressed
expressed in small intestine, placenta, spleen, cerebral cortex, ovary > uterus, mammary gland, stomach, cerebellum, whole brain > fetal brain, bone marrow, thyroid, thymus, heart, skeletal muscle, lung, liver, colon, pancreas, kidney, testis
not expressed in leukocytes
expressed in both normal & osteoarthritic cartilage
expressed at low level in chondrocytes in all zones of both normal & osteoarthritic cartilage