Urinary Glycoproteins

Urinary glycoprotein with FSH activity is chemically different from FSH isolated from pituitary tissue (R15), and it is likely that urinary... 

The most well-known urinary glycoprotein is the Tamm-Horsfall mucoprotein (THM). It is argued that the THM and uromucoid are both artifacts from the same native precursor and differ only in their sialic acid content (Kl). They are similar immunologically (Kl). The molecular mass of THM is 7 x 106 Da (Tl), with subunits of about 100,000 Da (F3). THM is synthesized by the cells of the thick ascending limb of Henle in the nephron (LI, R3). 

The concentration of urinary glycoproteins may play an important role in stone formation. Therefore, the level and activity of urinary proteases, for example, urokinase and plasmin, might be of great significance. According to this hypothesis, low activities or decreased production of urinary urokinase or plasmin may increase the urinary uromucoid concentrations, as well as stone formation. Increased levels of a urokinase inhibitor, namely urinary trypsin inhibitor (67,000 Da) and decreased urokinase activity in the urine of stone formers are well established (T2). Urinary urokinase activity was therefore studied, as well as the desialylation of urinary glycoproteins. (Fig. 4). 

Two serologically active urinary glycoproteins have been isolated from the urine of a patient suffering from tubular proteinuria. One of the glycoproteins had an JV-terminal amino-acid sequence with many similarities to that of another urinary glycoprotein (HC), in addition to analogous antigenic determinants. 

Morner isolated two water-soluble glycoproteins (called urinary mucoids) from urine by alcohol precipitation, redissolution, and precipitation with chloroform in the presence of acetic acid 4)- Interest in these substances was stimulated by the isolation of a purified urinary glycoprotein which proved to be a strong inhibitor of the hemagglutination by influenza virus and similar viruses 82, 83). Sialic acid (see below) is said to be removed from the glycoprotein by the virus. 

An A-acetylneuraminic acid has been isolated from bovine submaxillary mucin and the urinary glycoprotein (urinary mucoprotein of Tamm and Horsfall) following the enzymic action of the influenza virus on the glycoproteins 108), Gynaminic acid, from milk and meconium appear to be identical to the A-acetylneuraminic acid (sialic acid ) from sheep submaxillary gland and different from that from bovine submaxillary glands and lactaminic acid from bovine colostrum 102b, 109),... 

The urinary glycoproteins may also have a protective function for kidney tissues. These substances have been repeatedly implicated in kidney-stone formation. Thus, kidney stones and uromueoid have similar analyses (but with the former lacking sialic acid) luid uromueoid itself shows a marked tendency to inhibit calcium phosphate precipitation from supersaturated solutions, but does not do so after depolymerization (Gottsciialk, 1966, p. 458). 

Sialic acids are common in urinary glycoproteins in man (Tamm and Horsfall, 1950), rabbit (Cornelius et aL, 1965 Neuberger and Ratcliffe, 1972), cattle, horses, and sheep (Cornelius et aL, 1963 Mia and Cornelius, 1966 reviewed by Bourrillon, 1972). 

Bourrillon, R., 1972, Urinary glycoproteins, glycopeptides and related heterosaccharides, in Glycoproteins Their Composition, Structure and Function (A. Gottschalk, ed.), 2nd ed., pp. 909-925, Elsevier Publishing Co., Amsterdam. 

Bourrillon, R., Got, R., and Michon, J., 1961, Urinary glycoproteins. II. Study of a nondialyzable fraction soluble in 65% ethanol, Clin. Chim. Acta 6 91. 

Pape, L., and Maxfield, M., 1967, Neuraminidase action on the human urinary glycoprotein of Tamm and Horsfall, Biochim. Biophys. Acta 133 574-581. 

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