The extracellular domain is depicted in red and both heparan and chondroitin sulphate chains are indicated by the blue lines. Cleavage sites are indicated by purple blocks, followed by a short transmembrane domain in blue. Each syndecan has a short cytoplasmic domain in which a variable region is flanked by two highly conserved regions termed C1 and C2. Cleavage of the ectodomain can occur via numerous metalloproteinases such as MMP2, 3, 7 and 9, as well as proteases thrombin and plasmin. HS, Heparan sulphate; CS, Chondroitin sulphate; SDC, syndecan; TM, transmembrane.