Serum amyloid A-2 protein (SAA2) belongs to the SAA family. It expressed by the liver and secreted in plasma. SAA2 functions as major acute phase reactant and could works as apolipoprotein of the HDL complex. Increased levels of A-SAA in serum are indicative of inflammatory disease. When highly expressed, SAA can displace ApoA1 as the major apolipoprotein in HDL complexes, weakening the function of HDL as a reverse (lipid clearing) cholesterol transporter. A highly charged region of SAA2 and SAA1 (aa 36-68) contains putative fibronectin- and laminin-binding motifs. This region also binds heparin sulfate proteoglycans at mildly acidic pH and promotes aggregation of A-SAA.