Tive substrate, bacteriophage P1 RepA protein, have located DnaK- and DnaJ-binding sites in RepA (25). To gain further insight into chaperone functions in 32 degradation, we isolated many 32 mutants that are stable in vivo (26). These mutants contain one or two amino acid substitutions in the N-terminal half of Region 2.1. In this study, we examined the affinity of some mutant 32 for proteases and