TJP1, TJP2, and TJP3 are closely related scaffolding proteins that link tight junction (TJ) transmembrane proteins such as claudins, junctional adhesion molecules, and occludin to the actin cytoskeleton (, ). The tight junction acts to limit movement of substances through the paracellular space and as a boundary between the compositionally distinct apical and basolateral plasma membrane domains of epithelial and endothelial cells. Necessary for lumenogenesis, and particularly efficient epithelial polarization and barrier formation (By similarity). Plays a role in the regulation of cell migration by targeting CDC42BPB to the leading edge of migrating cells . Plays an important role in podosome formation and associated function, thus regulating cell adhesion and matrix remodeling . With TJP2 and TJP3, participates in the junctional retention and stability of the transcription factor DBPA, but is not involved in its shuttling to the nucleus (By similarity).
Subcellular locations: Cell membrane, Cell junction, Tight junction, Cell junction, Cell junction, Gap junction, Cell projection, Podosome
Moves from the cytoplasm to the cell membrane concurrently with cell-cell contact . At podosomal sites, is predominantly localized in the ring structure surrounding the actin core . Colocalizes with SPEF1 at sites of cell-cell contact in intestinal epithelial cells .
The alpha-containing isoform is found in most epithelial cell junctions. The short isoform is found both in endothelial cells and the highly specialized epithelial junctions of renal glomeruli and Sertoli cells of the seminiferous tubules.