Department of Biology, University of Maryland, College Park, Maryland, USA.
Biophys J. 2011 Nov 2;101(9):2163-9. doi: 10.1016/j.bpj.2011.09.041. Epub 2011 Nov 1.
When activated, the proapoptotic protein Bax permeabilizes the mitochondrial outer membrane, allowing the release of proteins into the cytosol and thus initiating the execution phase of apoptosis. When activated Bax was reconstituted into phospholipid membranes, we discovered a new, to our knowledge, property of Bax channels: voltage gating. We also found that the same Bax sample under the same experimental conditions could give rise to two radically different channels: Type A, which is small, well behaved, homogeneous, and voltage-gated, and Type B, which is large, noisy, and voltage-independent. One Type B channel can be converted irreversibly into a population of Type A channels by the addition of La(3+). This conversion process appears to involve a two-dimensional budding mechanism. The existence of these two types of Bax channels suggests a process for controlling the degree of mitochondrial outer membrane permeabilization.
当被激活时，促凋亡蛋白 Bax 使线粒体外膜通透，允许蛋白质释放到细胞质中，从而启动细胞凋亡的执行阶段。当激活的 Bax 被重建到磷脂膜中时，我们发现了 Bax 通道的一个新的、据我们所知的特性：电压门控。我们还发现，在相同的实验条件下，相同的 Bax 样本可能会产生两种截然不同的通道：A型，其特点是小、表现良好、均匀且电压门控，以及 B 型，其特点是大、嘈杂且与电压无关。通过添加 La(3+)，可以不可逆地将一个 B 型通道转换为一群 A 型通道。这个转换过程似乎涉及二维出芽机制。这两种 Bax 通道的存在表明了一种控制线粒体外膜通透性的程度的过程。
