Uroplakin-1a (UPK1A)

Uroplakin-1a (UPK1A) is a member of the tetraspanin family of four-pass transmembrane proteins, predominantly expressed in the apical membrane (asymmetric unit membrane, AUM) of differentiated urothelial (bladder epithelial) cells[1][3][4][5][6]. It forms a crucial structural component of urothelial plaques that provide a highly impermeable barrier protecting the bladder from its contents. UPK1A, together with its partner Uroplakin II, forms heterodimers that assemble into larger uroplakin complexes, ultimately shaping the rigid, crystalline plaques on the surface of umbrella cells[4][5][6]. This protein is implicated in cell signaling related to proliferation, differentiation, and response to stress, and provides a binding site for uropathogenic E. coli via mannose residues, making it central to the pathogenesis of urinary tract infections[5]. Reduced or altered expression has been observed in bladder cancers, and the protein is investigated as a marker of urothelial differentiation and a diagnostic tool. Although not currently a direct pharmacological target, understanding its structure and function is relevant for urological disease research and antimicrobial strategies.

Other names

Uroplakin-1aUP1aUPK1ATSPAN21Tspan-21UP1AUPKaUPIaUPIAUPKAtetraspanin-21Uroplakin Ia

Not currently a direct drug target. Attachment of E. coli FimH to N-glycosylated residues on Uroplakin-1a mediates initial steps of urinary tract infection, triggering downstream cellular responses including phosphorylation and apoptosis[5][4]