Perlecan (HSPG2) is a modular proteoglycan primarily located in the basement membranes of vascular tissues. It is involved in several developmental processes, both during embryogenesis and in human diseases such as cancer and diabetes (Iozzo et al. 1994). HSPG2 can self-aggregate into dimeric or multimeric forms (Yurchenco et al. 1987) and is involved in heterotypic interactions with numerous extracellular macromolecules (Whitelock et al. 2008, Perlecan entry in MatrixDB). HSPG2's GAG chains mediate interactions with fibroblast growth factor-2 (Vigny et al. 1988, Knox et al. 2002), and nidogens (Entactins, represented elsewhere). The core protein binds fibronectin (Isemura et al. 1987, Heremans et al. 1990, Vlodavsky et al. 1991), transthyretin (Smeland et al. 1997) and platelet-derived growth factor A and B homodimers (Göhring et al. 1998).