Major Histocompatibility Complex (MHC) class I molecules play a fundamental role in orchestrating the immune system and inducing protective immune responses against tumours and pathogens. They do this by presenting peptides derived from pathogen and tumour proteins to the immune system. TeamTAPBPR explores the pathway that controls peptide selection onto MHC-I molecules. This has important translational potential given the importance of MHC molecules in infectious disease, cancer and autoimmunity.