Chaperone activities of ClpB. The activities of firefly luciferase during its chaperone-assisted reactivation were monitored using luminescence (see Materials and Methods). Activities of rClpB alone; rClpB with DnaK; rClpB with DnaK, DnaJ, and GrpE (KJE); DnaK alone; and unheated luciferase alone are compared. The protein concentrations used were 33 nM luciferase, 2.0 μM ClpB, 2.0 μM M. genitalium rDnaK, 1.0 μM E. coli DnaK, 1.0 μM DnaJ, and 1.0 μM GrpE.