Evidence of differences between mannose-binding lectins from nodules and cotyledons of peanut

Abstract

The mannose/glucose-binding lectin (ML) from the nodules of peanut ( Arachis hypogaea L.) was found to be antigenically identical to ML from hypocotyls, stems, leaves and roots but cotyledon ML was antigenically different. The different tissue lectins had relative molecular weights similar to nodule ML and were each composed of two identical or nearly identical subunits. There were no differences between the set of multiple bands that each lectin formed during isoelectric focusing. The antigenically different cotyledon ML and nodule ML had similar carbohydrate specificities but differed in their sensitivity to haemagglutination inhibition by sugars and certain glycoproteins. In contrast, the antigenically identical leaf ML was identical to nodule ML in its reaction with sugars and glycoproteins. Nodule and cotyledon ML both contained mannose, galactose, fucose, xylose and acetylglucosamine although the proportions and content of sugars differed. The amino acid composition of nodule and cotyledon ML was similar but slight differences in their amino-terminal amino acid sequences suggested that they are produced by alleles of the same gene.