KEKE MOTIFS - PROPOSED ROLES IN PROTEIN-PROTEIN ASSOCIATION AND PRESENTATION OF PEPTIDES BY MHC CLASS-I RECEPTORS

A stretch of 28 'alternating' lysine (K) and glutamate (E) residues is found in an activator of the multicatalytic protease. Such 'KEKE sequ ences' are also present in subunits of the multicatalytic protease, in subunits of the 26S protease and in a variety of chaperonins. We prop ose that KEKE regions promote association between protein complexes. F urthermore, they may contribute to the selection of peptides presented on MHC Class I receptors.