Tight Junction Protein 3 (TJP3)

TJP3 is a member of the family of membrane-associated guanylate kinase-like proteins (MAGUK) that associate with intracellular junctions.Using a peptide sequence derived from a 130-kD protein that coimmunoprecipitated with TJP1 in canine kidney cells, Haskins et al. (1998) isolated canine Tjp3, which they called ZO3. The deduced 898-amino acid protein has a predicted molecular mass of 98 kD, although it runs anomalously at 130 kD by SDS PAGE. Canine Tjp3 shares 47% amino acid identity with human TJP1 and TJP2. The Tjp3 protein contains 3 PDZ domains, an SH3 domain, and a guanylate kinase (GUK) domain with high similarity to TJP1 and TJP2, as well as a unique proline-rich region between PDZ2 and PDZ3. Immunogold electro microscopy localized TJP3 with TJP1 to tight junctions in canine kidney cells.