Fig. 1.

Scheme of the urothelium and uroplakin plaque composition. Urothelium is composed of three layers: a basal cell layer attached to a basement membrane, an intermediate layer, and an apical layer with large hexagonal cells known as umbrella cells (a). The apical surface of umbrella cells creates a unique asymmetric unit membrane (AUM) composed of hexagonal plaques with six tetramers where two dimers UPIa/II and Ib/IIIa are linked (b). High-mannose N-glycan (light gray circle) on UPIa and complex N-glycans (dark gray circle) on UPIb and IIIa are depicted. Mature UPII lacks sugar moieties (c). Drown based on [22, 46]