We investigated the functional activity of recombinant Bax inhibitor-1 reconstituted into liposomes. When proteoliposomes were suspended in acidic solutions, encapsulated Ca 2+ was released from the membranes, as previously suggested [Kim HR, Lee GH, Ha KC, Ahn T, Moon JY, Lee BJ, Cho SG, Kim S, Seo YR, Shin YJet al. (2008) J Biol Chem 283, 15946–15955].