A hemagglutinin specific for sialic acids in a rat brain synaptic vesicle-enriched fraction |
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Authors: | Maurizio Popoli Angelo Mengano |
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Institution: | (1) Department of Neurology, Second School of Medicine, 80131 Napoli, Italy;(2) Clinica delle Malattie Nervose, Seconda Facoltà di Medicina, Via S. Pansini, 80131 Napoli, Italy |
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Abstract: | A hemagglutinating activity was detected in a synaptic vesicle-enriched fraction prepared from adult rat brain, using trypsinized glutaraldehyde-fixed rabbit erythrocytes. The specific activity of the fraction, in two series of experiments, was 7.5 and 16-fold higher than in the other subcellular fractions. The activity was absent from the synaptosome cytosol. In a study using twenty-five different carbohydrates and glycoproteins, best inhibitors were N-acetylneuraminic acid and N-glycolylneuraminic acid, together with bovine submaxillary mucin and a glycopeptide fraction prepared from rabbit erythrocyte membranes. The activity was thermolabile and very sensitive to proteolytic enzymes (but insensitive to neuraminidase) indicating that a protein (agglutinin) is responsible for the activity. Experiments using detergents and high ionic strength showed that the agglutinin is tightly bound to membranes, inactivated by the so-called non denaturing detergents, and stable in diluted sodium dodecyl sulphate. Hypotheses are discussed on the possible function of the agglutinin. |
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Keywords: | Synaptic vesicles lectin membrane proteins |
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