TJP2 (Tight Junction Protein 2), also known as Zona Occludens 2 or ZO2 is a protein that in humans is encoded by the TJP2 gene. Tight junction proteins (TJPs) belong to a family of membrane-associated guanylate kinase (MAGUK) homologs that are involved in the organization of epithelial and endothelial intercellular junctions. Duclos et al. (1994) mapped the TJP2 gene telomeric to the Friedreich ataxia critical region on chromosome 9q13-q21. TJP2 lies about 70 kb centromeric to the X123 gene and is transcribed in the centromere-to-telomere direction. Using in vitro assays and immunoprecipitation studies, Itoh et al. (1999) showed that the mouse Tjp1, Tjp2, and Tjp3 PDZ1 domains interacted with the C-terminal cytoplasmic domains of Cldn1 through Cldn8. In the mouse inner ear, Walsh et al. (2010) found that Tjp2 expression decreased rapidly between E16.5 and age 1 week to a level in adult mice that was approximately 50% of the level at birth (P0).