Tamm-Horsfall protein
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Tamm-Horsfall protein (THP), or Tamm-Horsfall mucoprotein, or uromodulin (Muchmore & Decker 1985) is a GPI-anchored glycoprotein which is not derived from blood plasma, but is produced by the thick ascending limb of the loop of Henle of mammalian kidney. When this protein is concentrated at low pH, it forms gel. Tamm-Horsfall protein is the most abundant protein in mammalian urine. It is the matrix of urinary casts derived from the secretion of renal tubular cells.
Uropontin, nephrocalcin and uromodulin are the 3 known urinary glycoproteins that affect the formation of calcium-containing kidney stones or calculus.
The protein was first purified by Tamm and Horsfall from healthy individuals (Tamms I & Horsfall FL, 1950). It was later detected in the urine of mammals studied.
The function of THP is not well known. Studies using THP-deficient mice revealed that THP is important to regulatory physiology and actually participates in transporter function [1].
