asymmetric unit membrane
A highly specialised biomembrane composed of uroplakins, which is produced by terminally differentiated urothelial cells. It plays an important role in cytoskeleton interaction in terminally differentiated urothelial cells, serves a mechanical function during the bladder distension-contraction cycles, and contributes to formation of urothelial glycocalyx which plays an important role in preventing bacterial adherence to urothelium.
The AUM explains the remarkable permeability barrier function of the urinary bladder. Bovine AUMs contain four major integral membrane proteins, i.e., uroplakins Ia, Ib, II, and IIIa; UPIa and Ib (both tetraspanins) form heterodimers with UPII and IIIa, respectively
Mol Biol Rep. 1996;23(1):3-11