Ubiquitin chain length holds key to antigen presentation

摘要

To activate T cells, both dendritic and B cells present surface markers comprised of antigen-derived peptides bound to histocompatibility complex class II (MHC II) molecules. But while so-called "immature" dendritic cells become activated by pathogens and downregulate ubiquitination to transport peptide-MHC II complexes to the plasma membrane, MHC II ubiquitination in B cells occurs continuously at the cell surface. In Ira Mellman's Inaugural Article, Jessica Ma et al.