The application of the peptide-linked beta 2-microglobulin (beta 2m) strategy is limited in some cases due to the incompatibility between the sequences of the peptides and the restriction sites of the plasmid vectors. An isocaudamer technique was adapted to overcome this restriction. Three peptide-linked beta 2m genes, HBc(18-27)-h beta 2m gene, OVA(257-264)-m beta 2m gene and HER2/neu(369-377)-m beta 2m gene, were inserted into the pET28a vectors with this technique. The corresponding proteins were expressed in Escherichia coli with yields of over 50 mg/l culture and purities of over 80%. This strategy facilitates the construction of peptide-linked beta 2m molecules and will simplify the preparation of major histocompatibility complex-peptide complexes.