Uroplakin II/UPII Recombinant Rabbit mAb (SDT-6121)

Uroplakin II (UPII) is a single-pass transmembrane protein encoded by the UPK2 gene (located on chromosome 11q23.3), with a molecular weight of approximately 19.4 kDa, and is a core constituent of the asymmetric unit membrane (AUM) of the urothelium. This protein is highly specifically expressed in terminally differentiated superficial cells (umbrella cells) of the urinary tract mucosa. Its extracellular domain forms an obligate heterodimer with the tetraspanin UPK1a, which is a prerequisite for its export from the endoplasmic reticulum and correct localization to the apical cell membrane. Functionally, UPII serves as a structural molecule involved in assembling the hexagonal plaque arrays on the asymmetric unit membrane; these plaques are thought to enhance the mechanical strength of the urothelial apical surface, preventing cell rupture during bladder filling. Because its expression is strictly restricted to tissues of urothelial origin, UPII has become a highly valuable immunohistochemical marker in pathological diagnosis for confirming the urinary tract origin of tumors. Studies have shown that the sensitivity of UPII in urothelial carcinoma is significantly superior to the traditional UPIII marker, with even higher detection rates in variant subtypes such as micropapillary and plasmacytoid, and it exhibits nearly 100% specificity, holding important application value in the differential diagnosis of metastatic urothelial carcinoma.