Uroplakins are transmembrane proteins in the cover cells of the urothelium. They belong to the group of the "transmembrane 4 superfamily" also known as tetraspanin family. Most of these proteins are "cell-surface proteins" characterized by 4 hydrophobic domains. Uroplakins are responsible for the mechanical chemical resistance of the urinary tract.
The uroplakin-3a antibody is a good marker for primary and metastatic urothelial carcinomas.