FIGURE 2.

Two vBcl-2 molecules bind the Beclin1 dimer; one with high and one lower affinity. A, binding isotherm using ITC for vBcl-2 in the injection syringe titrated into Beclin1 BH3-CCD in the cell. The data were fitted to a two-site binding model (lower panel). B, a complex of vBcl-2-Beclin1 BH3-CCD was co-purified and analyzed by sedimentation equilibrium. The data were fitted to a heterodimer model in which vBcl-2 bound by two separate events to the Beclin1 dimer. A representative fit is shown. C, ITC titration for vBcl-2 in the syringe and Beclin1 BH3 peptide in the cell, and the data were fitted to a single-site model.