Adiponectin, alternatively named Adipocyte Complement-Related Protein of 30 kDa, shares structural similarity with complement factor C1q and is a member of the family of defense collagens. It is secreted exclusively by differentiated adipocytes and circulates at high concentrations. Adiponectin has a modular structure comprising an N-terminal collagenous domain with multiple collagen triple helix repeats, followed by a C-terminal C1q-like globular domain. The globular domain has similar folding topology with tumor necrosis factor-? and assembles into homotrimers. Higher order oligomeric adiponectins are also formed via interactions between the collagenous stalk. A truncated form of Adiponectin containing only the globular domain can be generated by proteolytic cleavage.