MHC CLASS-I EXPRESSION IN MICE LACKING THE PROTEASOME SUBUNIT LMP-7

Proteasomes degrade endogenous proteins. Two subunits, LMP-2 and LMP-7 , are encoded in a region of the major histocompatibility complex (MHC ) that is critical for class I-restricted antigen presentation. Mice w ith a targeted deletion of the gene encoding LMP-7 have reduced levels of MHC class I cell-surface expression and present the endogenous ant igen HY inefficiently; addition of peptides to splenocytes deficient i n LMP-7 restores wild-type class I expression levels. This demonstrate s the involvement of LMP-7 in the MHC class I presentation pathway and suggests that LMP-7 functions as an integral part of the peptide supp ly machinery.