Arcelins are seed storage proteins found in certain wild bean accessions of Phaseolus vulgaris, and they play a role in conferring resistance to the Mexican bean weevil. Specifically, Arcelin 5, one of six arcelin electrophoretic variants, has been extensively characterized. The purified Arcelin 5 protein fraction consists of three major polypeptides: Arcelin 5a (32.2 kDa), Arcelin 5b (31.5 kDa), and Arcelin 5c (30.8 kDa). These three polypeptides share the same isoelectric point and exhibit identical N-terminal amino acid sequences.

Three lines P. vulgaris was used G2771 (CIAT genebank accession number), Advanced/improved cultivar ICA PIJAO G5773 and BC1F1 line which was obtained by crossing G2771 with ICA PIJAO, and subsequently back-crossing to ICA PIJAO. This line contains phaseolin, phytohemagglutinin, and arcelin 5 and is resistant to Z. subfasciatus.

Arcelin 5a and Arcelin 5b are glycoproteins, while Arcelin 5c lacks glycosylation. The native form of Arcelin 5 exists as a dimer. By employing amino acid sequence analysis and PCR techniques, two distinct cDNA sequences for Arcelin 5, designated arc5-4 and arc5-ZZ, were obtained. Both sequences encode proteins of 261 amino acids with a 21-amino acid signal peptide. These two cDNAs share a high degree of similarity, with a 99% identity at the DNA level and a 97% identity in their deduced amino acid sequences. Arc5-Z and Arc5-ZZ cDNAs correspond to Arcelin 5a and Arcelin 5b, respectively.

Comparisons of sequences and protein characteristics indicate that Arcelin 5 is related to, yet distinct from, other arcelin variants and lectins found in Phaseolus vulgaris.