Integral transmembrane proteoglycans (syndecan-1, 310 aa) that link the extracellular matrix with the actin cytoskelton and act as receptors or coreceptors in intracellular communication. The extracellular domain has multiple heparan sulphate and two chondroitin or dermatan sulphate chains plus an N-linked oligosaccharide, and binds to collagens, fibronectin, and tenascin. Binding of heparin-binding growth-associated molecule to N-syndecan (syndecan-3, 442 aa) increases phosphorylation of c-*src and cortactin, and N-syndecan may act as a neurite outgrowth receptor. Four members of the syndecan family show a remarkable physical relationship with four members of the myc gene family. Syndecans bind gp120 of HIV and act as mediators for viral adsorption. Syndecan-4 (amphiglycan, ryudocan, 198 aa) was isolated from human epithelial and fibroblastic cells. Syndecan-binding protein (syntenin, melanoma differentiation-associated protein 9, scaffold protein Pbp1, 298 aa) is an adaptor protein with tandem repeat of PDZ domains that binds the cytoplasmic domain of syndecans and of pro-TGFα (see transforming growth factor).
Subjects: Medicine and Health.