GAL GLYCOCONJUGATES

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The purpose of this project is to study glycoconjugates with the Gal alpha 1 leads to 3Gal epitope in mammals. These compounds are of special interest because of their unique evolutionary distribution. They are prevalent in some tissues of non-primate mammals and New World monkeys. In contrast, man, apes and Old World monkeys have this epitope only in a cryptic, vestigial form. Moreover, Old World monkeys, apes and man produce usually large amounts of a naturally occurring antibody (anti-Gal) to this structure. Preliminary studies in man have shown that the interaction between anti-Gal and Gal alpha 1 leads to 3Gal epitopes exposed de novo, mediates the removal of normal senescent red cells and, under certain circumstances, may promote accelerated removal of pathologic red cells. Recently we have produced a mouse monoclonal antibody (Gal-13) which has the same binding specificity as anti-Gal, recognizing exclusively Gal alpha 1 leads to 3Gal glycoconjugates. This monoclonal antibody will be a useful tool for the research described in this application. Three approaches will be used to study the distribution, structure and biosynthesis of these glycoconjugates in mammals. 1) Taxonomical and histochemical analyses will be done by immunostaining with anti-Gal and Gal-13 on several tissues and cell lines obtained from various mammals. Parallel staining studies will be performed with the lectin, Bandeiraea simplicifolia I-B4, which seems to display a specificity similar, but not identical, to that of anti-Gal. 2) Structural analyses of Gal alpha 1 leads to 3Gal glycoconjugates will be done on glycolipids and glycoproteins isolated from red cells, brain and kidney tissue of selected mammals. 3) Analysis of the biosynthesis of Gal alpha 1 leads to 3Gal glycoconjugates will be done by studying the tissue distribution of alpha 1 leads to 3 galactosyl-transferase, purification of this enzyme and characterization of its substrate specificity. These studies will provide comprehensive information on the evolutionary and biochemical aspects of Gal alpha 1 leads to 3Gal glycoconjugates in mammals. Subsequent studies on Gal alpha 1 leads to 3Gal glycoconjugates in human tissues will be based on the information obtained in this project.