Saturation binding of mouse JE to rabbit CCR2. Various concentrations of 125I-mouse JE was added to U-937/rabbit CCR2 stable transfectants as described under "Materials and Methods". The nonspecific binding was determined by including 100-fold excess of unlabeled chemokine. Specific binding was calculated by subtracting nonspecific binding from total binding. The dissociation constant (K
) was calculated using the nonlinear curve fit. Each point represents mean values of the duplicates from one of two representative assays. The scatchard plot is depicted in the insert.