Sequence analysis of arcelin 2, a lectin-like plant protein.

The nucleotide sequence of the cDNA clone encoding arcelin 2 (Arc2), one member of a family of closely related lectin-like plant toxins from wild bean accession, is presented. The sequence contains a 265-amino acid (aa) open reading frame and is 99.3% homologous to Arc1, another of the four electrophoretic variants with proven antibiosis characters. These two proteins differ by four aa residues. Based on cross hybridizations of RNAs, it is assumed that Arc4 is more divergent than Arc1 and Arc2. Furthermore, it is likely that at least three of the variants are polypeptides of similar size and the observed molecular weight differences between them are due to differences in the number of glycosylation sites.