TAPBPR promotes antigen loading on MHC-I molecules using a peptide trap

Abstract

The molecular chaperones tapasin and TAPBPR play important roles in defining the repertoire of peptides displayed by MHC class I. Here, the authors combine NMR, ITC, fluorescence polarization measurements and deep mutational scanning analyses to reveal a peptide editing mechanism, where the G24-R36 loop in TAPBPR acts as a molecular trap to promote the selection of high-affinity peptide cargo.