Mitogenic properties of two carbohydrate binding proteins from the Dolichos biflorus plant

Abstract

Most lectins described to this date have been isolated from the seeds of leguminous plants. One such lectin is the glycoprotein isolated from the seeds of the Dolichos biflorus plant expressing an activity for terminal non-reducing a-linked Nacetyl-D-galactosamine residues [ 11. In addition to this seed lectin the stems and leaves of the Dolichos bijlorus plant contain another glycoprotein that crossreacts with antibodies against the lectin from the seeds of this plant. This cross-reactive material (CRM) was isolated and characterized 121 and was shown to have an amino acid and carbohydrate composition very similar to that of the seed lectin 12~31. CRM and the seed lectin both contain apparently equal amounts of two types of subunits; one CRM subunit is identical in electrophoretic mobility to subunit I of the seed lectin [2]. Both CRM subunits have. a NHz-terminal amino acid sequence identical to the sequence of the seed lectin subunits with the exception of an aspartate in place of an asparagine at the second residue [2,4]. It has also recently been shown that CRM, at low ionic strength, has carbohydrate binding activity [S] although its specificity is somewhat broader that that of the seed lectin. Despite this close structural resemblance between these two carbohydrate binding proteins