Functions in biogenesis and organization of the apical membrane of epithelial cells of the thick ascending limb of Henle's loop (TALH), where it promotes formation of complex filamentous gel-like structure that may play a role in the water barrier permeability. May serve as a receptor for binding and endocytosis of cytokines (IL-1, IL-2) and TNF. Facilitates neutrophil migration across renal epithelia.
In the urine, may contribute to colloid osmotic pressure, retards passage of positively charged electrolytes, and inhibits formation of liquid containing supersaturated salts and subsequent formation of salt crystals. Protects against urinary tract infections by binding to type 1 fimbriated E.coli. Binds to bacterial adhesin fimH which mediates the stable formation of bacterial aggregates, prevents the binding of E.coli to uroplakins UPK1A and UPK1B which act as urothelial receptors for type I fimbriae, and allows for pathogen clearance through micturation. Also promotes aggregation of other bacteria including K.pneumoniae, P.aeruginosa and S.mitis and so may also protect against other uropathogens.
Subcellular locations: Apical cell membrane, Basolateral cell membrane, Cell projection, Cilium membrane
Only a small fraction sorts to the basolateral pole of tubular epithelial cells compared to apical localization. Secreted into urine after cleavage. Colocalizes with NPHP1 and KIF3A.
Subcellular locations: Secreted
Detected in urine.