Crompton Martin, Barksby Emma, Johnson Nicholas, Capano Michela
Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
Biochimie. 2002 Feb-Mar;84(2-3):143-52. doi: 10.1016/s0300-9084(02)01368-8.
Mitochondria establish contact sites between the inner and outer membranes. The contact sites are held together by junctional complexes of the adenine nucleotide translocase (ANT; inner membrane) and the voltage-dependent anion channel (VDAC; outer membrane). The junctional complexes act as multifunctional recruitment centres, binding a range of proteins according to the function to be executed. Some of these, involving kinases and enzymes of lipid transfer, are readily understood as ongoing functions in energy and lipid metabolism. But the roles of other proteins recruited to the junctional complexes are less well defined. Here, we focus on the complexes formed with Bax and with cyclophilin-D, and their possible roles in apoptotic and necrotic cell death. We have isolated both types of complexes using glutathione-S-transferase fusion proteins of Bax and of cyclophilin-D. The VDAC/ANT/cyclophilin-D complex reconstitutes Ca(2+)- and cyclosporin A-sensitive permeability transition pore activity when incorporated into proteoliposomes. The complex forms readily in the absence of factors required for pore opening in isolated mitochondria, suggesting that these factors act on the preexisting complex, rather than drive its assembly, and that the complex is a physiological entity in healthy cells.
线粒体在内膜和外膜之间建立接触位点。这些接触位点由腺嘌呤核苷酸转位酶（ANT；内膜）和电压依赖性阴离子通道（VDAC；外膜）的连接复合物维系在一起。这些连接复合物充当多功能招募中心，根据要执行的功能结合一系列蛋白质。其中一些涉及激酶和脂质转移酶，很容易理解为能量和脂质代谢中的持续功能。但招募到连接复合物的其他蛋白质的作用尚不太明确。在这里，我们重点关注与 Bax 和亲环蛋白 D 形成的复合物，以及它们在凋亡性和坏死性细胞死亡中的可能作用。我们使用 Bax 和亲环蛋白 D 的谷胱甘肽 - S - 转移酶融合蛋白分离出了这两种类型的复合物。当 VDAC/ANT/亲环蛋白 D 复合物整合到蛋白脂质体中时，可重构对 Ca(2+) 和环孢素 A 敏感的通透性转换孔活性。该复合物在分离的线粒体中形成孔开放所需因子缺失的情况下很容易形成，这表明这些因子作用于预先存在的复合物，而不是驱动其组装，并且该复合物是健康细胞中的一种生理实体。
