Empty and peptide-containing conformers of class I major histocompatibility complex molecules expressed in Drosophila melanogaster cells.

Transfected Drosophila melanogaster cells can express large quantities of class I major histocompatibility complex molecules. Such molecules lack endogenous peptides because the Drosophila cells are devoid of proteins necessary for intracellular peptide loading. The empty molecules are efficiently expressed on the cell surface and can acquire extracellular peptides. The conformation and stability of empty murine class I molecules are determined by the source of beta 2-microglobulin. All beta 2-microglobulin-induced conformers of empty heavy chains seem to be unified in a common rigid conformation on peptide binding.