The mitochondrial inner membrane is a protein-rich environment containing large multimeric complexes, including complexes of the mitochondrial electron transport chain, mitochondrial translocases and quality control machineries. Although the inner membrane is highly proteinaceous, with 40-60% of all mitochondrial proteins localised to this compartment, little is known about the spatial distribution and organisation of complexes in this environment. We set out to survey the arrangement of inner membrane complexes using stochastic optical reconstruction microscopy (STORM). We reveal that subunits of the TIM23 complex, TIM23 and TIM44 (also known as TIMM23 and TIMM44, respectively), and the complex IV subunit COXIV, form organised clusters and show properties distinct from the outer membrane protein TOM20 (also known as TOMM20). Density based cluster analysis indicated a bimodal distribution of TIM44 that is distinct from TIM23, suggesting distinct TIM23 subcomplexes. COXIV is arranged in larger clusters that are disrupted upon disruption of complex IV assembly. Thus, STORM super-resolution microscopy is a powerful tool for examining the nanoscale distribution of mitochondrial inner membrane complexes, providing a 'visual' approach for obtaining pivotal information on how mitochondrial complexes exist in a cellular context.

中文翻译：

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超分辨率显微镜揭示了哺乳动物线粒体内膜蛋白复合物的排列。

线粒体内膜是一个富含蛋白质的环境，含有大型多聚体复合物，包括线粒体电子传递链、线粒体转位酶和质量控制机制的复合物。尽管内膜的蛋白质含量很高，所有线粒体蛋白质的 40-60% 都位于该区室，但人们对该环境中复合物的空间分布和组织知之甚少。我们开始使用随机光学重建显微镜（STORM）来调查内膜复合物的排列。我们揭示了 TIM23 复合物的亚基 TIM23 和 TIM44（也分别称为 TIMM23 和 TIMM44）以及复合物 IV 亚基 COXIV 形成有组织的簇，并显示出与外膜蛋白 TOM20（也称为 TOMM20）不同的特性。基于密度的聚类分析表明 TIM44 的双峰分布与 TIM23 不同，表明存在不同的 TIM23 子复合物。COXIV 排列成较大的簇，当复杂的 IV 组装被破坏时，这些簇就会被破坏。因此，STORM超分辨率显微镜是检查线粒体内膜复合物纳米级分布的强大工具，为获取线粒体复合物如何在细胞环境中存在的关键信息提供了“视觉”方法。