The invention is an assay designed to identify agents that modulate apoptosis. The invention provides an assay system and methods for screening for inhibitors of the Bcl-2 family of proteins. In various aspects the invention provides an assay system containing a liposome reagent and an immobilized BH3 domain peptide. In further aspects the invention provides an assay system containing mitochondria, an immobilized BH3 domain peptide and a mitochondrial binding agent, e.g. an anti-VDAC anti-body.
