Syndecan--a cell surface proteoglycan that selectively binds extracellular effector molecules.

Abstract

Syndecan is a cell surface proteoglycan (Saunders et al., 1989), which was originally isolated from mouse mammary epithelial (NMuMG) cells as a hybrid proteoglycan containing both heparan sulfate and chondroitin sulfate glycosaminoglycan (GAG) chains (Rapraeger et al., 1985). The ratio and total amount of GAG bound to syndecan is known to vary in different tissues (Sanderson & Bernfield, 1988; Salmivirta et al., 1991) and cells (Rapraeger 1989). Syndecan binds several extracellular matrix molecules such as fibrillar collagens of interstitial matrix (Koda et al., 1985), fibronectin (Saunders & Bernfield, 1988) and thrombospondin (Sun et al., 1989) but shows no binding to some other heparin binding matrix molecules, like vitronectin and laminin (Koda et al., 1985; Elenius et al., 1990). Syndecan also binds growth factors, like bFGF (Kiefer et al., 1990), and could therefore play a major role in the regulation of cell adhesion, growth and differentiation (for a review see Jalkanen et al., 1991).