PathwayStep1022 PathwayStep1032 Hyaluronan uptake and degradation Hyaluronan biosynthesis and export Hyaluronan metabolism Authored: Jassal, B, 2012-02-24 Edited: Jassal, B, 2012-02-24 GENE ONTOLOGYGO:0030212 Hyaluronan (hyaluronic acid, hyaluronate or HA) is an anionic glycosaminoglycan (GAG) distributed widely throughout connective, epithelial, and neural tissues and most abundant in the extracellular matrix and skin. HA is unique among the GAGs in that it is not sulfated and is not found covalently attached to proteins as a proteoglycan. HA polymers are very large (they can reach molecular weights of 10 million Da) and can displace a large volume of water making them excellent lubricators and shock absorbers. Another unique feature of HA is that it is synthesized at the plasma membrane unlike other GAGs which are formed in the Golgi. HA is a polymer of the disaccharide unit D-glucuronic acid and D-N-acetylglucosamine, linked via alternating beta-1,4 and beta-1,3 glycosidic bonds (Toole 2000, 2004, Volpi et al. 2009). Pubmed10930435 Pubmed15229478 Pubmed19442142 Reactome Database ID Release 432142845 Reactome, http://www.reactome.org ReactomeREACT_121083 Reviewed: D'Eustachio, P, 2012-03-28