Use at an assay-dependent concentration. For Sandwich ELISA pairing: Human Complement factor D Antibody(Capture) (EPA1649C), with Human Complement factor D Protein (EPA1649S) as assay standards. The reference range value is 39.1-5,000 pg/mL.
Target info
Function
Complement factor D (FD; also called adipsin) is a trypsin-family (S1) serine protease encoded by the human CFD gene. It is secreted mainly by adipocytes of white adipose tissue and, to a lesser extent, by macrophages and hepatocytes into blood plasma; uniquely among complement proteases it is secreted in its mature, active form rather than as a zymogen, and it has the lowest plasma concentration of all complement components. Its sole and rate-limiting substrate is complement factor B: when factor B is bound to C3b (or C3(H2O)) on a target surface, factor D cleaves FB into Ba and Bb, generating the alternative pathway C3 convertase C3bBb and thereby initiating the alternative pathway amplification loop. Beyond immunity, adipsin functions as an adipokine: it is secreted by fat cells and regulates triglyceride clearance and glucose transport through C3aR/C5aR2-mediated signaling, and has been linked to insulin secretion and adipose-tissue metabolic homeostasis. Subcellularly, factor D is a secreted circulating plasma protein acting in the fluid phase and on C3b-decorated surfaces.
