The ribosomal protein P0 of soybean (Glycine max L. Merr.) has antigenic cross-reactivity to soybean seed lectin
1997
Wycoff, K.L. | Van Rhijn, P. | Hirsch, A.M.
Soybean (Glycine max L. Merr.) mutants lacking the ability to produce the lectin normally found in soybean seeds (SBL) are designated Le(-). A protein of higher molecular weight that cross-reacts with antibodies raised to SBL was found at nearly equivalent levels in roots, hypocotyls, and leaves, and at lower levels in cotyledons and dry seeds of both Le(+) and Le(-) soybean cultivars. Earlier work suggested that this protein was a novel lectin. Clones isolated from a Le(-) soybean root cDNA library produced a cross-reacting protein of the same size in Escherichia coli. Sequence analysis of these clones revealed a high degree of similarity to the ribosomal protein P0. The cross-reacting protein co-purified with ribosomes, and a monoclonal antibody raised to purified brine shrimp P0 cross-reacted to the same protein. The protein showed no lectin activity in a hemagglutination assay, nor did it bind to an N-acetyl-D-galactosamine affinity column. On the basis of this evidence, we conclude that the SBL-cross-reacting protein is not a lectin but a homologue of the ribosomal protein P0. Consequently, Le(-) soybeans must produce a lectin that is dissimilar to SBL at both the DNA and amino acid levels and we suggest that it is this lectin which is involved in nodulation.
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