Hosta

N-Acetylgalactosamine (GalNAc), is an amino sugar derivative of galactose.

Function

In humans it is the terminal carbohydrate forming the antigen of blood group A.^[1]

It is typically the first monosaccharide that connects serine or threonine in particular forms of protein O-glycosylation.

N-Acetylgalactosamine is necessary for intercellular communication, and is concentrated in sensory nerve structures of both humans and animals.

GalNAc is also used as a targeting ligand in investigational antisense oligonucleotides and siRNA therapies targeted to the liver, where it binds to the asialoglycoprotein receptors on hepatocytes. ^[2]

^ Donald M. Marcus; Elvin A. Kabat; Gerald Schiffman (1964). "Immunochemical Studies on Blood Groups. XXXI. Destruction of Blood Group A Activity by an Enzyme from Clostridium tertium Which Deacetylates N-Acetylgalactosamine in Intact Blood Group Substances". Biochemistry. 3 (3): 437–443. doi:10.1021/bi00891a023.
^ Nair, Jayaprakash K; Willoughby, Jennifer L. S; Chan, Amy; Charisse, Klaus; Alam, Md. Rowshon; Wang, Qianfan; Hoekstra, Menno; Kandasamy, Pachamuthu; Kel'In, Alexander V; Milstein, Stuart; Taneja, Nate; o'Shea, Jonathan; Shaikh, Sarfraz; Zhang, Ligang; Van Der Sluis, Ronald J; Jung, Michael E; Akinc, Akin; Hutabarat, Renta; Kuchimanchi, Satya; Fitzgerald, Kevin; Zimmermann, Tracy; Van Berkel, Theo J. C; Maier, Martin A; Rajeev, Kallanthottathil G; Manoharan, Muthiah (2014). "Multivalent N-Acetylgalactosamine-Conjugated siRNA Localizes in Hepatocytes and Elicits Robust RNAi-Mediated Gene Silencing". Journal of the American Chemical Society. 136 (49): 16958–16961. doi:10.1021/ja505986a. PMID 25434769.