Human Apo-SAA is a 104 amino acid polypeptide that circulates primarily in association with high-density lipoproteins (HDL). The level of Apo-SAA, normally 1–5 μg/ml in plasma, increases 500–1000 fold within 24 hours of an inflammatory stimulus and, under these conditions, is the most abundant HDL apolipoprotein. The human SAA gene codes for a 122 amino acid polypeptide, which contains an 18 amino acid N-terminal signal sequence. Recombinant Apo-SAA is a consensus SAA molecule corresponding to human Apo-SAA1α, except for the presence of an N-terminal methionine, the substitution of asparagine for aspartic acid at position 60, and arginine for histidine at position 71 (the latter two substituted residues are present in Apo-SAA2β). The calculated molecular weight of Recombinant Human Apo-SAA is 11.7 kDa.
Amino Acid Sequence
Tested by its ability to down-regulate lipid biosynthesis in aortic smooth muscle cells. The effective concentration was found to be 4 µM.* * Schreiber, BM. et al. Biochem J. 1999 Nov 15; 344 Pt 1:7–13