Tight junction-associated protein 1 is a protein that in humans is encoded by the TJAP1 gene. This gene encodes a tight junction-associated protein. Incorporation of the encoded protein into tight junctions occurs at a late stage of formation of the junctions. The encoded protein localizes to the Golgi and may function in vesicle trafficking. Alternatively spliced transcript variants have been described. A related pseudogene exists on the X chromosome.