[Tamm-Horsfall protein].
Human Tamm-Horsfall glycoprotein, the major urinary protein, is a glycosyl-phosphatidyl-inositol (GPI) - anchored membrane protein which mainly resides at the luminal face of cells of the thick ascending limb of Henle's loop (TAL) and early distal convoluted tubules of nephron. Tamm-Horsfall protein contains exclusively N-linked glycans, mainly of polyantennary type largely sialylated and fucosylated, but also high-mannose glycans. Only a portion of the Tamm-Horsfall protein is released as soluble protein by the action of proteases and in a minor amount by a cell-associated GPI-specific phospholipase. The physiological function of Tamm-Horsfall glycoprotein has not been clarified to date. Since the urinary Tamm-Horsfall protein has a high gel-forming tendency, it has been postulated that it takes part in the water impermeability of TAL. It is also proposed that the Tamm-Horsfall protein plays a protective role towards pyelonephritogenic pathogens such as Escherichia coli. The Tamm-Horsfall protein may inhibit the colonization of these pathogens in the renal mucosa in that the soluble form competes with that exposed at the plasma membrane. Recently, urinary Tamm-Horsfall protein has been implicated in tubulointerstitial nephritis.
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Laboratoire de biochimie, Hôpital Armand-Trousseau, 26, avenue du Dr-Arnold-Netter, 75012 Paris, France.
D006801:Humans; D009088:Mucoproteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D014570:Urologic Diseases / Q000209:etiology; D058949:Uromodulin
D009088:Mucoproteins; C548612:UMOD protein, human; D058949:Uromodulin