Figure 2.

Exchange of bound radiolabeled GroES₇ as a function of added unlabeled GroES. Plot shows radiolabeled GroES₇ retained in GroES₇–GroEL₁₄ complex vs. the ratio of added unlabeled GroES to radiolabeled GroES₇. The initial sample contained 0.34 μM GroEL₁₄ and 1.7 μM radiolabeled GroES₇ in the same buffer as in Fig. 1. The abscissa gives the ratio of added unlabeled GroES₇ over the initial radiolabeled GroES₇. Units of the ordinate are counts from the PhosphorImager output. Electrophoresis was performed as in Fig. 1, and the radiolabel was quantified as described in Materials and Methods. Actual data are represented by ▴; theoretical expectations for isotopic equilibration are represented by ⧫. The line is an exponential fit to the data.