G. Reeke, J. W. Becker, B. A. Cunningham
Jun 1, 1974
Citations
1
Influential Citations
75
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Journal
Annals of the New York Academy of Sciences
Abstract
Concanavalin A (Con A ) , the lectin of the jack bean (Canavalia ensiformis), is one of the most widely used of the plant agglutinins in biological studies of eukaryotic cells. This protein has a number of activities that are useful for studies of cell surfaces and cell division. These activities, which may proceed by a variety of mechanisms, all appear to be dependent on the initial binding of Con A to specific saccharide-containing receptors on the cell surface, for they can be inhibited by appropriate specific monosaccharides such as D glucose and D-mannose, but no; by related compounds such as D-galactose.’ and germ line cells,3 presumably by virtue of its multiple valence for cell surface receptors, but frequently there are differences in the agglutinability of normal, trypsinized, or virus-transformed cells of the same cell line.4. These differences appear to arise from variations in the distribution, rather than in the number, of Con A receptors on the various types of cell.G-s Con A can also bind to adipocytes, with which it is as effective as insulin in enhancing the rate of glucose transport and inhibiting epinephrine-stimulated lipolysis.” Con A is a competitive inhibitor of insulin binding to these cells, and the lectin binding is itself inhibited by a-methylmannoside.” Perhaps the most extensively studied activity of Con A is its ability to induce mitogenesis in lymphocytes,10. l1 a phenomenon analogous to the stimulation of immune cells by specific antigens. It is striking that the binding of Con A to lymphocytes alters the mobility and distribution of various receptor molecules on the cell surface. Under appropriate conditions, Con A in low doses forms “caps” with its own glycoprotein receptors.12* l 3 On the other hand, higher concentrations of Con A inhibit the formation of “patches” and “caps” induced on lymphocytes by antibodies and other reagent^.'^ All of these properties of Con A make it a powerful probe for studies of the cell surface and of the regulation of cell metabolism and cell division. In order to understand the molecular basis for the activities of Con A, we have undertaken extensive studies of its structure and function. We have recently reported the amino acid sequence and complete three-dimensional structure of Con A.I5 We have also prepared chemically modified forms of Con A, with altered subunit structure and altered biological properties.lX The results of these studies have suggested a number of useful hypotheses for further analysis of the biological activities of Con A. It has been found that Con A can agglutinate a variety of somatic *,