SAA4 is a constitutively expressed protein belonging to the SAA family. It is a major acute phase reactant and an apolipoprotein of the HDL complex. SAA4 is constitutively expressed only in humans and mice, is associated almost entirely with lipoproteins of the high density range. Its physiological function is unknown and its serum concentration has no relationship with those of other major apolipoproteins. The presence of SAA4 mRNA and protein in macrophage derived foam cells of coronary and carotid arteries suggested a specific role of human SAA4 during inflammation including atherosclerosis. Recombinant human SAA4 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques. Synonyms: Serum amyloid A-4 protein , C-SAA, CSAA. NCBI no.: NP_006503