Fetuin-A

Mouse Fetuin A, also known as α2-Heremans-Schmid glycoprotein, is encoded by the AHSG gene. It has been also called "countertrypsin" because of its ability to inhibit trypsin. It is a major plasma protein and a member of the cystatin superfamily of protease inhibitors. It is expressed by hepatocytes, the principal cell source, and by monocyte/macrophages. The major form of plasma Fetuin A corresponds to two disulfide bondlinked chains derived from the single chain. FetuinA has a number of functions. It is a negative acutephase protein with normal circulating levels in adults (300-600 μg/mL), which fall significantly (30-50%) during injury and infection. It enhances entry of cationic inhibitors into macrophages. It inhibits both insulin receptor autophosphorylation and undesirable calcification.