<p>Each GroEL sample was incubated for 2 h at 37°C with an equimolar concentration of GroES. After incubation, samples were partitioned by centrifugal concentration (100 kDa cutoff). Samples denoted "Conc." indicate a 24 µg aliquot of each sample recovered from the upper reservoir concentrate of the filtering apparatus. Samples denoted "Filt." represent proteins that were recovered from a 200 µl aliquot of the lower reservoir filtrate of the apparatus. Experiments were performed in the absence (<i>−ATP, A</i>) and presence (<i>+ATP, B</i>) of 0.2 mM ATP. <i>RW</i> indicates GroEL R231W, and <i>CP</i> indicates GroEL CP376-RW samples. The apparent molecular weights of a commercial marker mixture (Dalton VII molecular weight marker, Sigma) are indicated to the left of the figure.</p
