HAS1

Hyaluronan synthase 1 is an is_associated_with::enzyme that in humans is encoded by the HAS1 is_associated_with::gene.

Structure
Hyaluronan or is_associated_with::hyaluronic acid (HA) is a high molecular weight unbranched is_associated_with::polysaccharide synthesized by a wide variety of organisms from bacteria to mammals, and is a constituent of the is_associated_with::extracellular matrix. It consists of alternating glucuronic acid and N-acetylglucosamine residues that are linked by beta-1-3 and beta-1-4 glycosidic bonds. HA is synthesized by membrane-bound is_associated_with::synthase at the inner surface of the plasma membrane, and the chains are extruded via ABC-transporter into the extracellular space.

Function
It serves a variety of functions, including space filling, lubrication of is_associated_with::joints, and provision of a matrix through which cells can migrate. HA is actively produced during is_associated_with::wound healing and tissue repair to provide a framework for ingrowth of blood vessels and is_associated_with::fibroblasts. Changes in the serum concentration of HA are associated with inflammatory and degenerative is_associated_with::arthropathies such as is_associated_with::rheumatoid arthritis. In addition, the interaction of HA with the leukocyte receptor is_associated_with::CD44 is important in tissue-specific homing by is_associated_with::leukocytes, and overexpression of HA receptors has been correlated with tumor is_associated_with::metastasis. HAS1 is a member of the newly identified vertebrate gene family encoding putative hyaluronan synthases, and its amino acid sequence shows significant homology to the hasA gene product of is_associated_with::Streptococcus pyogenes, a glycosaminoglycan synthetase (DG42) from is_associated_with::Xenopus laevis, and a recently described murine hyaluronan synthase.