Figure 5.

The Bak α9:α9 interface is not impeded when an antibody inhibits the BH3:groove interface. Membrane fractions from Bak^−/−Bax^−/− MEFs expressing the indicated cysteine variants were incubated without or with tBid. Where indicated, an anti-BH3 (4B5) or control antibody to the Bak N terminus (8F8)²⁴ was also present (at 5 μg per 50 μl sample) during the incubation. Aliquots were assessed for cysteine linkage by CuPhe as in Figure 3a, or for cytochrome c release. Mx indicates an intramolecular cysteine disulfide bond (C14:C166) in nonactivated wt Bak. Data are representative of at least three independent experiments