EPITOPE MAPPING OF HUMAN ETS1 MONOCLONAL-ANTIBODY

The epitope for E44 monoclonal antibody (mAb) was mapped using mutated ETS1 proteins lacking different carboxy-terminal regions and by the e mployment of synthetic oligopeptides spanning the epitope region. This epitope lies around Arg211 of the human ETS1 protein since substituti on of Arg211 by Gln211 in the epitope region results in the loss of re cognition of the mouse ETS1 protein by E44 mAb. Substitution of Leu214 by valine214 in the epitope region (as is found in the chicken ETS1 a nd viral Ets proteins) does not alter the capacity of the E44 mAb to r ecognize this antigen. Taken together, these results suggest that a sp ecific ionic interaction is able to play a pivotal role in the recogni tion of the ETS1 protein by the E44 mAb.