Multifunctional adapter protein involved in diverse array of functions including trafficking of transmembrane proteins, neuro and immunomodulation, exosome biogenesis, and tumorigenesis . Positively regulates TGFB1-mediated SMAD2/3 activation and TGFB1-induced epithelial-to-mesenchymal transition (EMT) and cell migration in various cell types. May increase TGFB1 signaling by enhancing cell-surface expression of TGFR1 by preventing the interaction between TGFR1 and CAV1 and subsequent CAV1-dependent internalization and degradation of TGFR1 . In concert with SDC1/4 and PDCD6IP, regulates exosome biogenesis . Regulates migration, growth, proliferation, and cell cycle progression in a variety of cancer types . In adherens junctions may function to couple syndecans to cytoskeletal proteins or signaling components. Seems to couple transcription factor SOX4 to the IL-5 receptor (IL5RA) . May also play a role in vesicular trafficking . Seems to be required for the targeting of TGFA to the cell surface in the early secretory pathway .
Subcellular locations: Cell junction, Focal adhesion, Cell junction, Adherens junction, Cell membrane, Endoplasmic reticulum membrane, Nucleus, Melanosome, Cytoplasm, Cytosol, Cytoplasm, Cytoskeleton, Secreted, Extracellular exosome, Membrane raft
Mainly membrane-associated. Localized to adherens junctions, focal adhesions and endoplasmic reticulum. Colocalized with actin stress fibers. Also found in the nucleus. Identified by mass spectrometry in melanosome fractions from stage I to stage IV. Associated to the plasma membrane in the presence of FZD7 and phosphatidylinositol 4,5-bisphosphate (PIP2) .
Expressed in lung cancers, including adenocarcinoma, squamous cell carcinoma and small-cell carcinoma (at protein level) . Widely expressed. Expressed in fetal kidney, liver, lung and brain. In adult highest expression in heart and placenta.