Adiponectin is a 28 kD is a complement 1q family member that is involved in the control of fat metabolism and insulin sensitivity. Adiponectin forms multimers, under non-reducing, non-heat denaturing conditions with approximate molecular weights of >300 kD, 167 kD, and 67 kD. Under reducing conditions with no heat, adiponectin is approximately 67 kD; under reducing conditions with heat, the adiponectin monomer has an apparent molecular weight of approximately 28 kD. Adiponectin can be modified by glycosylation and hydroxylation. Adiponectin is synthesized and secreted into plasma by adipocytes. Adiponectin has also been shown to act as a negative regulator of hematopoiesis and inflammation. In macrophages and endothelial cells adiponectin has been shown to downregulate TNF-induced adhesion molecules, and block NF-kappaB signaling though a cAMP-dependent mechanism. Decreased levels of adiponectin are associated with obesity insulin resistance and type 2 diabetes. IL-6 inhibits adiponectin production and secretion. Adiponectin has been shown to interact with collagen type I, III, and V. The Poly6215 antibody has been shown to be useful for Western blotting of human adiponectin.