Jj. Grootjans et al., SYNTENIN, A PDZ PROTEIN THAT BINDS SYNDECAN CYTOPLASMIC DOMAINS, Proceedings of the National Academy of Sciences of the United Statesof America, 94(25), 1997, pp. 13683-13688
The syndecans are transmembrane proteoglycans that place structurally
heterogeneous heparan sulfate chains at the cell surface and a highly
conserved polypeptide in the cytoplasm. Their versatile heparan sulfat
e moieties support various processes of molecular recognition, signali
ng, and trafficking. Here we report the identification of a protein th
at binds to the cytoplasmic domains of the syndecans in yeast two-hybr
id screens, surface plasmon resonance experiments, and ligand-overlay
assays. This protein, syntenin, contains a tandem repeat of PDZ domain
s that reacts with the FYA C-terminal amino acid sequence of the synde
cans. Recombinant enhanced green fluorescent protein (eGFP)-syntenin f
usion proteins decorate the plasmamembrane and intracellular vesicles,
where they colocalize and cosegregate with syndecans. Cells that over
express eGFP-syntenin show numerous cell surface extensions, suggestin
g effects of syntenin on cytoskeleton-membrane organization. We propos
e that syntenin may function as an adaptor that couples syndecans to c
ytoskeletal proteins or cytosolic downstream signal-effectors.