Native and/or asialo-Tamm-Horsfall glycoproteins Sd(a +) are important receptors for Triticum vulgaris (wheat germ) agglutinin and for three toxic lectins (abrin-a, ricin and mistletoe toxic lectin-I)

Abstract

The binding properties of human Tamm-Horsfall Sd(a +) urinary glycoprotein (THGP) and asialo-THGP with Triticum vulgaris agglutinin(WGA) and three toxic lectins (abrin-a, ricin, and Mistletoe toxic lectin-I) were investigated by quantitative precipitin and precipitin inhibition assays. Both glycoproteins reacted strongly with abrin-a, precipitating over 80% of the lectin nitrogen tested. THGP also bound well to mistletoe toxic lectin-I and precipitated 86% of this lectin added, while the precipitability of its asialo product decreased by 28%. The native glycoprotein completely precipitated the WGA added, but its reactivity was reduced dramatically after desialylation. On the contrary, the poor reactivity of THGP with ricin increased substantially after removal of sialic acid and completely precipitated the lectin added. The glycoprotein-lectin interactions were inhibited by one or several of the following haptens, p-NO 2-phenyl αGalNAc, p-NO 2-phenyl βGalNAc, Gal β1→4GlcNAc, Galβ1→4Glc, GlcNAc β1→4GlcNAc, and/or GlcNAc. From the above results, it is concluded that native and/or asialo Tamm-Horsfall glycoproteins serve as important receptors for these three toxic lectins and for WGA.