The Ad2 E3-19k pro tein in hib its the trans port of newly syn the sized class I MHC mol e cules to the cell surface, thereby in ter fer ing with an ti gen pre sen ta tion. The de tails of the in ter ac tion be tween E3-19k pro tein and class I MHC mol e cules have not been well-defined. In this pres ent study, we de scribe the use of gel fil tra tion HPLC for con firm ing the bind ing in ter ac tion of two do main pro teins, E3-19k and MHC class I an ti gen, and sub se quently the char ac ter iza tion of pro tein com plex by SDS-PAGE. Our re sults dem on strate the com plex for ma tion be tween Ad2 lumenal E3-19k (108 amino ac ids, wt 108) and HLA-A*0201 mol e cule in vi tro. Ti tration ex per i ments will be em ployed in the fu ture to de ter mine stoichiometry and ver ify the spe cific in ter actions.Jour nal of the Chi nese Chem i cal So ci ety, 2002, 49, 607-610 AC KNOWL EDG MENTS