Elution profiles of purification of the refolded equine MHC I complex (ELA-A1*7-6, mouse β2m and EIAV Env-RW12 epitope) by Superdex 200 16/60 HiLoad gel-filtration and Resource Q anion-exchange chromatography (GE Healthcare). (a) Gel-filtration profile of the refolded products. Peak 1 contains aggregated heavy chain, peak 2 contains the correctly refolded complex (44 kDa) and peak 3 contains the abundant β2m. Insert: reduced SDS–PAGE gel (15%) of the corresponding purified protein from each peak. Lane M contains molecular-weight markers (labelled in kDa). (b) Results of further purification of the refolded complex by anion-exchange chromatography. The complex was eluted at an NaCl concentration of 19.0–22.5%. Insert: reduced SDS–PAGE gel (15%) of protein from the peak.