Using CFEs from yeast expressing one of the three mutant eEF1As resulted in ,3-fold increased TBSV repRNA accumulation when compared with the extract obtained from yeast expressing the wt copy of eEF1A ( Fig. 2A , lanes 2-4 versus 5). These data suggest that the viral replicase complex containing the mutant eEF1A can support in vitro TBSV repRNA replication more efficiently than the replicase with the wt eEF1A. In contrast, CFE from N21 yeast supported TBSV repRNA replication to similar extent as the CFE containing wt eEF1A ( Fig. 2A , lanes 1 versus 5), indicating that N21 eEF1A mutant can perform the same functions as the wt eEF1A in vitro, when the same amount of p33 and p92 pol was provided.