Analysis of lectin-specific cell surface glycoprotein on neuroblastoma cells |
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Authors: | P Maher RS Molday |
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Institution: | Department of Biochemistry, University of British Columbia, Vancouver, B.C. V6T 1W5 Canada |
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Abstract: | The binding sites for the lectins wheat germ agglutinin, Ricinus communis agglutinin and concanavalin A on mouse neuroblastoma cell membranes were identified using SDS-gel electrophoresis in combination with fluorescent lectins. Ricinus communis agglutinin and wheat germ agglutinin were found to bind almost exclusively to a single polypeptide with an apparent molecular weight of 30 000. Concanavalin A labeled over 20 different polypeptides, most with molecular weights greater than 50 000. However, when the neuroblastoma cells were treated with concanavalin A so as to internalize all the concanavalin A binding sites visible at the level of the fluorescent microscope and the purified plasma membranes analyzed for their concanavalin A binding polypeptides, only four of the 20 glycopolypeptides were missing or significantly reduced in amount. Thus, these four high molecular weight concanavalin A-binding polypeptides appear to be the major cell surface receptors for concanavalin A. Binding studies with iodinated concanavalin A indicated that these polypeptides represented the high affinity concanavalin A binding sites ). Low affinity concanavalin A binding sites were present on the cell surface after internalization of high affinity concanavalin A binding sites. |
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Keywords: | Lectin binding site Glycoprotein Cell surface (Neuroblastoma cell) |
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