Major histocompatibility (MHC) class II molecules can exist in two distinct conformational states based on alternative pairing of transmembrane domain GxxxG dimerization motifs (i.e., M1- and M2-paired MHC class II). M1- and M2-paired MHC class II molecules drive different levels of T cell activation and B cell signaling
consequently, differential peptide loading would impact the level of immune response elicited by various antigens/epitopes. In previous studies of a single model antigen, we show that while peptide from BCR-bound antigen is selectively loaded onto M1-paired I-A