APO-SAA Human Active Protein

This gene encodes a member of the serum amyloid A family of apolipoproteins. The encoded protein is a major acute phase protein that is highly expressed in response to inflammation and tissue injury. This protein also plays an important role in HDL metabolism and cholesterol homeostasis. High levels of this protein are associated with chronic inflammatory diseases including atherosclerosis, rheumatoid arthritis, Alzheimer's disease and Crohn's disease. This protein may also be a potential biomarker for certain tumors. Alternate splicing results in multiple transcript variants that encode the same protein. A pseudogene of this gene is found on chromosome 11.[provided by RefSeq, Jun 2012]

SAA1: Major acute phase reactant. Apolipoprotein of the HDL complex. Reactive, secondary amyloidosis is characterized by the extracellular accumulation in various tissues of the SAA1 protein. These deposits are highly insoluble and resistant to proteolysis; they disrupt tissue structure and compromise function. Elevated serum SAA1 protein levels may be associated with lung cancer. Belongs to the SAA family.

Protein type: Secreted; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 11p15.1

Cellular Component: extracellular region

Molecular Function: heparin binding; G-protein-coupled receptor binding

Biological Process: positive regulation of interleukin-1 secretion; receptor-mediated endocytosis; neutrophil chemotaxis; platelet activation; elevation of cytosolic calcium ion concentration; regulation of protein secretion; positive regulation of cell adhesion; negative regulation of inflammatory response; acute-phase response; innate immune response; lymphocyte chemotaxis; macrophage chemotaxis; positive regulation of cytokine secretion