Complement 3 (C3) through its interaction with factors B and D (adipsin) generates C3a. In the human body, C3a is rapidly cleaved by carboxypeptidase B or carbxyopeptidase N, that remove the carboxyl-terminal arginine to generate C3adesArg.[1] Thus, most of plasmatic C3a is present in C3adesArg form. C3adesArg is more commonly named ASP or acylation-stimulating-protein due to its marked stimulating action on triacylglycerol synthesis in human adipocytes and skin fibroblasts.[2] ASP is also known for its augmentation of glucose transport and inhibiting action on hormone-sensitive lipase. Because of these actions, it is linked to the pathogenesis of obesity,[3] having been demonstrated to be present at increased levels in patients with obesity,[4] diabetes mellitus type 2[5] and coronary artery disease.[6]
ASP lis a ligand for C5L2, a G-protein-coupled receptor.[7]
The view of C3a/C3adesArg as an acylation stimulating activity is not universally accepted. The evidence is discussed in a recent review.[8]