C1qTNF9, also known as CTRP9, is one of several Adiponectin/Acrp30 paralogs which comprise the C1q and TNF-related protein family. All family members share a modular organization comprising a short variable region, a collagenous domain, and a C1q-like globular domain. C1qTNF9 is a 40 kDa glycoprotein that contains multiple hydroxylated proline residues in its collagenous region. It circulates as a homotrimer and higher order multimers as well as in heterotrimers with Adiponectin. It is preferentially expressed in adipose tissue and plays a role in glucose homeostasis. Human C1qTNF9 shares 85% amino acid sequence identity with mouse and rat C1qTNF9.