protein_function: Cell surface proteoglycan that bears heparan sulfate.
Syndecan-4 (SDC4) is a protein that in humans is encoded by the SDC4 gene. The protein is found as a homodimer and is a member of the syndecan proteoglycan family. It is mapped to 20q13.12. Syndecan-4 is one of the four vertebrate syndecans and has a molecular weight of ~20 kDa. It is a transmembrane (type I) heparan sulfate proteoglycan that functions as a receptor in intracellular signaling. Syndecan-4 also regulates the actin cytoskeleton, cell adhesion, and cell migration. In addition, Syndecan-4 can activate protein kinase C (PKC). The variable domain of syndecan-4 could be a site of self-association. What??s more, Syndecan-4 also binds to phosphatidylinositol (4,5)-bisphosphate (PIP2) through the variable domain and increases PKC activity ten-fold.