The impetus for putting together this special issue entitled “Mitochondria and friends” is the sad recent passing of Walter Neupert in 2019. Walter Neupert (Figure 1), together with his colleague, competitor, and scientific friend, Gottfried Schatz, founded and dominated the field of mitochondrial biogenesis for several decades. As a student, Walter Neupert joined the laboratory of Theodor Bücher in Munich (himself a student of Otto Warburg) in the 1960s when it was discovered with great surprise that mitochondria contain DNA. One of Walter Neupert’s first projects as a student was to try to establish a culture medium that would allow him to cultivate and grow mitochondria outside of cells, working on the assumption that mitochondria might have retained the capacity to grow autonomously just like bacteria (Neupert 2012). Of course, this experiment failed. Anecdotally, it was this failure that gave rise to more than 50 years of extremely successful research. Walter Neupert discovered that mitochondria have to import most of their proteins from the cytosol. He identified protein translocases in the outer (TOM) and inner (TIM) membranes of mitochondria, as well as proteases, chaperones and assembly factors that drive the translocation, processing, folding and assembly of these proteins. He was particular fascinated by the mechanisms by which mitochondrial precursor proteins are recognized by TOM receptors on the outer membrane, threaded through the translocation channels of the TOM and TIM complexes and finally sorted into their respective mitochondrial subcompartments. Evolutionary tinkering, how he used to call it, and the obvious parallels between mitochondria and bacteria always inspired Walter Neupert. He studied mitochondrial ribosomes and the membrane insertion and assembly of their translation products, the insertion of heme cofactors into cytochromes, the folding andmembrane insertion of βbarrel proteins as well as the bacteria-like sorting of proteins from the matrix to the mitochondrial intermembrane space (Wagener et al. 2011). However, no other project was as close to his heart as the discovery of themechanisms and factors that fold the mitochondrial inner membrane into cristae and constitute the inner-to-outer membrane contact sites (Khosravi and Harner 2020). The discovery of the MICOS complex and the specific function of the ATPase and the respiratory chain in bending and structuring the inner membrane thrilled him until the end, as documented by hundreds of fountain pen drawings of mitochondrial ultrastructures in his notebook (see front cover of this issue). His enthusiasm, meticulous research and devotion to mitochondria shaped and inspired a whole research field. Many of his pupils contributed to this issue, which encompasses numerous research topics that were initially pioneered by Walter Neupert. The title ‘Mitochondria and friends’was also the name of a symposium held in Munich in 2009, on the occasion of Walter Neupert’s 70th birthday (see Figure 2). We hope this issue can serve as a fitting

中文翻译：

---

线粒体和朋友——纪念 Walter Neupert (1939–2019) 的特刊

将这个名为“线粒体和朋友”的特刊放在一起的动力是 Walter Neupert 最近在 2019 年不幸去世。 Walter Neupert（图 1）与他的同事、竞争对手和科学朋友 Gottfried Schatz 一起创立并主导了几十年的线粒体生物发生领域。作为一名学生，Walter Neupert 在 1960 年代加入了位于慕尼黑的 Theodor Bücher（他本人是 Otto Warburg 的学生）的实验室，当时他惊讶地发现线粒体含有 DNA。Walter Neupert 作为学生的第一个项目是尝试建立一种培养基，使他能够在细胞外培养和生长线粒体，假设线粒体可能保留了像细菌一样自主生长的能力（Neupert 2012 ）。当然，这个实验失败了。有趣的是，正是这种失败导致了 50 多年的极其成功的研究。Walter Neupert 发现线粒体必须从细胞质中输入大部分蛋白质。他鉴定了线粒体外膜 (TOM) 和内膜 (TIM) 中的蛋白质转位酶，以及驱动这些蛋白质易位、加工、折叠和组装的蛋白酶、分子伴侣和组装因子。他对线粒体前体蛋白被外膜上的 TOM 受体识别、穿过 TOM 和 TIM 复合物的易位通道并最终分类到它们各自的线粒体亚室中的机制特别着迷。进化修补，他过去怎么称呼它的，线粒体和细菌之间明显的相似之处总是启发 Walter Neupert。他研究了线粒体核糖体及其翻译产物的膜插入和组装、血红素辅因子插入细胞色素、β桶蛋白的折叠和膜插入以及蛋白质从基质到线粒体膜间隙的细菌样分选（Wagener等人，2011 年）。然而，没有其他项目像发现将线粒体内膜折叠成嵴并构成内外膜接触位点的机制和因素一样接近他的心脏（Khosravi 和 Harner 2020）。MICOS 复合物的发现以及 ATP 酶和呼吸链在弯曲和构建内膜方面的特定功能使他激动到最后，正如他笔记本中数百幅线粒体超微结构钢笔画所记录的那样（见本期封面）。他的热情、细致的研究和对线粒体的奉献塑造并启发了整个研究领域。他的许多学生都为这个问题做出了贡献，其中包含许多最初由 Walter Neupert 开创的研究课题。2009 年，在 Walter Neupert 诞辰 70 周年之际，在慕尼黑举行的一场研讨会的名称是“线粒体和朋友”（见图 2）。我们希望这个问题可以作为一个合适的 其中包含许多最初由 Walter Neupert 开创的研究课题。2009 年，在 Walter Neupert 诞辰 70 周年之际，在慕尼黑举行的一场研讨会的名称是“线粒体和朋友”（见图 2）。我们希望这个问题可以作为一个合适的 其中包含许多最初由 Walter Neupert 开创的研究课题。2009 年，在 Walter Neupert 诞辰 70 周年之际，在慕尼黑举行的一场研讨会的名称是“线粒体和朋友”（见图 2）。我们希望这个问题可以作为一个合适的