Syndecans have attached heparan sulfate (HS) and to a lesser extent chondroitin sulfate (CS) chains. These allow interactions with a large number of proteins. Syndecans are also signalling molecules, interacting with cytoplasmic proteins. Most studies have involved syndecan-4 (Multhaupt et al. 2009). Zebrafish and murine syndecan-4 V regions bind the membrane lipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) undergoing a shape change revealed by NMR spectroscopy (Oh et al. 1998, Whiteford et al. 2008). The resulting complex is able to bind protein kinase C alpha which is persistently activated in the absence of Ca2+ (Oh et al. 1997, Lee et al. 1998, Keum et al. 2004).