Properties of the tapasin homologue TAPBPR

- TAPBPR is a second MHC class I-dedicated chaperone in the antigen processing and presentation pathway.
- Like tapasin, TAPBPR acts as a peptide editor and influences the final peptide repertoire displayed on the surface of cells.
- In contrast to tapasin, TAPBPR is not a component of the peptide-loading complex and therefore regulates novel aspects of antigen processing and presentation.

The presentation of antigenic peptides by MHC class I molecules plays a vital role in generating T cell responses against infection and cancer. Over the last two decades the central role of tapasin as a peptide editor that influences the loading and optimisation of peptides onto MHC class I molecules has been extensively characterised. Recently, it has become evident that the tapasin-related protein, TAPBPR, functions as a second peptide editor which influences the peptides displayed by MHC class I molecules. Here, we review the discovery of TAPBPR and current understanding of this novel protein in relation to its closest homologue tapasin.

85