Adiponectin, also referred to as Acrp30, AdipoQ and GBP-28, is a recently discovered 244 aminoacid protein, the product of the apM1 gene, which is physiologically active and specifically and highly expressed in adipose cells. The protein belongs to the soluble defence collagen superfamily; it has a collagen-like domain structurally homologous with collagen VIII and X and complement factor C1q-like globular domain. Adiponectin forms homotrimers, which are the building blocks for higher order complexes found circulating in serum. Together, these complexes make up approximately 0.01% of total serum protein. Adiponectin receptors AdipoR1 and AdipoR2 have been recently cloned; AdipoR1 is abundantly expressed in skeletal muscle, whereas AdipoR2 is predominantly expressed in the liver. Paradoxically, adipose tissue-expressed adiponectin levels are inversely related to the degree of adiposity. Adiponectin concentrations correlate negatively with glucose, insulin, triglyceride concentrations, liver fat content and body mass index and positively with high-density lipoprotein-cholesterol levels, hepatic insulin sensitivity and insulin-stimulated glucose disposal.

Sequence: EDDVTTTEEL APALVPPPKG TAAGWMAGIP GHPGHNGTPG RDGRDGTPGE KGEKGDAGLL GPKGETGDVG MTGAEGPRGF PGTPGRKGEP GEAAYMYRSA FSVGLETRVT VPNVPIRFTK IFYNQQNHYD GSTGKFYCNI PGLYYFSYHI TVYMKDVKVS LFKKDKAVLF TYDQYQEKNV DQASGSVLLH LEVGDQVWLQ VYGDGDHNGL YADNVNDSTF TGFLLYHDTN DYKDDDDK

Other names: Adipocyte C1q and collagen domain-containing protein, Adipocyte complement-related 30 kDa protein, ACRP30, Adipose most abundant gene transcript 1 protein, apM-1, Gelatin-binding protein, ADIPOQ, ACDC, APM1, GBP28