In Vitro Expression and Purification of Class I MHC Molecules

The major histocompatibility complex (MHC) is a gene family responsible for many critical functions of the immune system in most vertebrates. The MHC consists of three classes differentiated by their structure and function, and MHC class I encodes antigen binding proteins as well as chaperone and accessory proteins such as tapasin. The purpose of this project is to reconstitute several human MHC class I molecules in their peptide-filled and peptide-deficient forms, and to purify these proteins for biochemical study. The expressed proteins include wild type and mutant variants of the fusion protein human leukocyte antigen HLA-B*0801-fos, and human beta-2-microglobulin (β2m). The major experiments performed for this project include: 1) transformation of engineered plasmids into competent cells; 2) large scale protein production; 3) extraction and purification of proteins as inclusion bodies; 4) reconstitution of proteins into their native structure; 5) purification of refolded proteins. The purified MHC class I molecules can be used to study their interactions with transmembrane chaperone and accessory proteins that reside in the endoplasmic reticulum for the purpose of better understanding the class I antigen presentation pathway