Van Venetië R, Verkleij A J
Biochim Biophys Acta. 1982 Nov 22;692(3):397-405. doi: 10.1016/0005-2736(82)90390-x.
The possible role of non-bilayer phospholipids on the structure of isolated rat liver mitochondria has been morphologically studied. Freshly isolated freeze-fractured mitochondria show smooth fracture faces with particles, representing the limiting membranes. The frequency and size of the particles is representative for the various membrane faces. Distinctly large particles and pits represent the attachment sites of cristae to the inner membrane. Liposome-like structures in the matrix are found upon incubation with Ca2+ and Mn2+. At 5 mM Mn2+ and more, curved hexagonal (HII) phase tubes are observed. Subsequent addition of 1 mM EDTA results in disappearance of the HII tubes, and liposomal structures can again be seen. These findings are interpreted in terms of an Mn2+-induced lamellar to HII phase transition. Patchwork-like structures characterize the membranes of mitochondria, quenched from 37 degrees C, as well as those incubated with Ca2+, Mn2+, Mg2+ and apo- or cytochrome c. This phenomenon is interpreted as being the result of the fracture plane, jumping from the outer to the inner limiting membrane and vice versa at sites of contact. A semi-fusion model, in which non-bilayer lipids are involved, is proposed for these contact sites.
已对非双层磷脂在分离的大鼠肝线粒体结构中可能发挥的作用进行了形态学研究。新鲜分离的经冷冻断裂的线粒体显示出带有颗粒的光滑断裂面，这些颗粒代表了界限膜。颗粒的频率和大小代表了不同的膜面。明显较大的颗粒和凹坑代表嵴与内膜的附着位点。与Ca2+和Mn2+一起孵育时，在基质中发现了脂质体样结构。在5 mM Mn2+及更高浓度下，观察到弯曲的六方（HII）相管。随后加入1 mM EDTA会导致HII管消失，并且脂质体结构再次可见。这些发现可根据Mn2+诱导的片层到HII相转变来解释。拼接样结构是从37℃淬灭的线粒体膜以及与Ca2+、Mn2+、Mg2+和脱辅基或细胞色素c一起孵育的线粒体膜的特征。这种现象被解释为断裂平面在接触位点从外界限膜跳到内界限膜，反之亦然的结果。针对这些接触位点提出了一个涉及非双层脂质的半融合模型。
