| Modification Notes |
SIMP (source of immunodominant MHC-associated peptides), also known as STT3B (STT3, subunit of the oligosaccharyltransferase complex, homolog B), is an 826 amino acid multi-pass membrane protein that localizes to the endoplasmic reticulum and belongs to the STT3 family. Expressed in liver, heart, placenta, kidney, brain, muscle and pancreatic tissue, SIMP exists as a component of the multi-protein oligosaccharyltransferase (OST) complex and functions to catalyze the N-glycosylation of target proteins. More specifically, SIMP mediates the transfer of high mannose oligosaccharides from lipid-linked oligosaccharide donors to target asparagine residues on polypeptide chains. The gene encoding SIMP maps to human chromosome 3, which houses over 1,100 genes, including a chemokine receptor (CKR) gene cluster and a variety of human cancer-related gene loci. |