生物膜能量偶联ATP酶的比较研究——Ⅱ.鼠肝线粒体ATP酶(F_1)与人原发性肝癌线粒体内膜的杂交重组及其对肝癌发生的遗传控制的初步分析

1974到1975年,我们用人原发性肝癌细胞的线粒体内膜进行ATP酶活力测定,结果证明人肝癌线粒体ATP酶活力极低(0.04～0.1微克分子/分/毫克蛋白)只相当于正常大鼠线粒体的1/10～1/25(0.49～1.07微克分子/分/毫克蛋白)。Walker肉瘤和人肝硬变组织的线粒体与人肝癌的酶活力相近。电镜负染标本观察证明肝癌线粒体内膜大部分失去特征性的直径为90(?)的ATP酶颗粒,表现为光滑膜。ANS萤光探针的发射萤光光谱测定和2,4-二硝基酚的激活试验均证明人肝癌细胞线粒体内膜的ATP酶大量消失是肝癌细胞的特征之一。用提取的大鼠肝线粒体ATP酶(F_1)与人肝癌线粒体内膜进行人工杂交重组,结果证明,重组后的杂交膜的ATP酶活力比人肝癌线粒体内膜高6～11倍;寡霉素敏感性也显著提高。电镜负染标本观察表明杂交膜出现了典型的直径为90(?)的ATP酶的颗粒形态;ANS萤光增强效应测定证明杂交膜的萤光强度比肝癌膜高276%(相对单位);0℃低温处理2小时,ANS萤光强度不变;酶活力在0℃2小时后,仍相当于原来活力的90%。此项试验结果证明杂交重组获得成功。鼠肝线粒体ATP酶与人肝癌线粒体内膜杂交后的特性表现了与天然线粒体内膜的ATP酶的一系列相似的特性。讨论了ATP酶复合体杂交重组试验在探索肝癌发生与细胞中两个遗传系统控制的可能关系问题。     

生物膜能量偶联ATP酶的比较研究——Ⅰ.鼠肝线粒体内膜与ATP酶(F_1)的人工重组及ANS萤光探针与ATP酶的结合

本文报导了大鼠肝线粒体内膜ATP酶的析离和重组,以及膜对ATP酶的结构和功能的影响。用(1)胰蛋白酶-尿素、(2)硅钨酸盐和(3)枯草杆菌蛋白酶三种方法分别制备的去ATP酶(F_1)的线粒体内膜与可溶性的F_1重组后,完全恢复或部分恢复到天然线粒体内膜的ATP酶活力水平。寡霉素敏感性测定、ANS结合的发射萤光光谱测定、电镜负染标本观察和低温处理试验等都一致证明,ATP酶与膜重组后表现了一系列与天然膜相似的性质。ANS萤光探针与线粒体内膜结合的萤光增强效应主要在于ANS与ATP酶(F_1)的结合并与F_1的分子构象有密切关系。经胰蛋白酶-尿素处理去掉F_1的线粒体内膜基本上丧失了ANS的萤光增强效应。可溶性F_1经0℃处理2小时后,丧失酶水解活力的84%和ANS萤光增强效应的96.4%。F_1与膜结合后,则表现了对0℃低温的稳定性。结果提示,ANS可能与ATP酶分子的疏水微区相结合;ATP酶分子疏水结构的存在对于表现酶的水解活力和ANS的萤光增强效应是必要的条件;低温处理破坏了酶分子内的疏水结构;膜与ATP酶结合则有稳定酶分子的疏水结构和分子构象的作用。     

中华眼镜蛇毒膜毒素对鼠肝线粒体膜的作用位点的研究

中华眼镜蛇毒膜毒素C(MT-C)对鼠肝完整线粒体的呼吸有明显抑制作用,但不影响完整线粒体的氧化磷酸化活力以及线粒体碎片上F_1-ATP酶的活力表现。根据膜毒素(MT-C)明显地抑制Ca~(++)诱导下的线粒体6态呼吸速度和质子释放,本文认为膜毒素(MT-C)在鼠肝线粒体上的真正作用位点可能位于内膜上Ca~(++)的结合位点附近,而不在呼吸酶系或磷酸化酶系本身。     

克山病是一种“心肌线粒体病(Mitochondrial Cardiomyopathy)”

亚急克病人心肌线粒体内膜电子传递链的琥珀酸氧化酶系,琥珀酸脱氢酶和细胞色素氧化酶活性明显低于对照。H~ -ATP酶的活性及其对寡霉素的敏感性都明显下降。ATP能量化后线粒体膜电位的变化也比对照明显降低。膜脂流动性低于对照。亚急克病人心肌线粒体内观察到较多的电子致密无定形物质,经电镜X射线微区等方法分析,认为这些物质不是Ca_3(PO_4)_2,而可能是一种蛋白质凝聚物。此外,心肌线粒体的硒含量远低于对照,而Ca含量明显高于对照。上述结果都反映亚急克病人心肌线粒体明显损伤。根据克山病患者心肌细胞线粒体结构与功能方面呈现的如此广泛与明显的异常,可将克山病称为“心肌线粒体病(Mitochondrial Cardiomyopathy)”。     

生物膜能量偶联 ATP 酶的研究:鼠肝线粒体 ATP 酶(F_1)的解离和重组

纯化的鼠肝线粒体ATP 酶(F_1)在1MKCl-TEA 缓冲液(Tris-SO_4~-,50mM;EDTA,1mM;ATP,2mM;pH=7.6)中,2～3℃下处理40～90分钟丧失ATP 水解活力,比活力从70～100下降到0.5～1.0。7%聚丙烯酰胺凝胶电泳证明,随着酶活力的下降和F_1的电泳酶带的消失,在凝胶柱上出现三条F_1的解离蛋白带。解离后的F_1于30℃对TEA(pH5.7)介质透析脱盐能重新出现有活力的F_1,活力恢复到原来酶活力的19～22%,此种重组的F_1在pH 中性偏碱条件下保持稳定。重组过程不需外加Mg~( )的促进和SH 基的保护。重组的F_1与去F_1的Tu 膜可重新结合,完全恢复原来线粒体内膜的ATP 酶水解活力和对DCCD 的敏感性。     

硫化氢对低温胁迫下甜樱桃柱头和子房线粒体功能的影响

为探索低温胁迫下外源硫化氢(H₂S)对甜樱桃花的柱头和子房线粒体功能的影响,本研究以甜樱桃品种‘早大果’花枝为试材,在-2 ℃低温下喷施0.05 mmol·L^-1硫氢化钠(NaHS,H₂S供体)和15 μmmol·L^-1 次牛磺酸(HT、H₂S清除剂),测定柱头和子房线粒体中活性氧、抗氧化酶和线粒体膜通透性转换孔(MPTP)开放程度、膜流动性、膜电位和细胞色素(Cyt c/a)比值变化。结果表明: 低温胁迫导致线粒体内过氧化氢(H₂O₂)和丙二醛(MDA)含量显著增加,线粒体MPTP明显增大,膜流动性降低,膜电位和线粒体Cyt c/a吸光度比值、膜H⁺-ATPase活性显著下降,线粒体结构受到损伤。低温胁迫下,外施0.05 mmol·L^-1 NaHS可显著降低低温胁迫下柱头和子房线粒体H₂O₂和MDA含量,在较长时间内维持较高的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性,减小线粒体MPTP开放程度,增强线粒体膜流动性,提高线粒体膜电位、Cyt c/a值和膜H⁺-ATPase活性;NaHS清除剂HT则抵消NaHS对上述参数的影响。综上所述,外源H₂S可以提高低温胁迫下甜樱桃柱头和子房线粒体抗氧化酶活性,减少H₂O₂和MDA积累,提高膜H⁺-ATPase活性,稳定线粒体膜结构和功能,进而缓解低温胁迫对花器官的伤害。     

NG-硝基-L-精氨酸对大鼠局灶性缺血脑区线粒体损伤的影响

目的:观察非选择性一氧化氮合酶抑制剂NG-硝基-L-精氨酸(NG-nitro-L-arginine,L-NA)对局灶性脑缺血大鼠脑线粒体的损伤作用,以探讨其改善缺血性脑损伤的作用机制。方法:将大鼠随机分为假手术组、缺血对照组、L-NA治疗组,采用线栓法阻断大鼠大脑中动脉(MCAO)复制局灶性脑缺血模型,分别于缺血后2h、6h、12h给药治疗3d,迅速断头取脑,差速离心法提取缺血侧脑组织线粒休,迅速测定线粒体膜肿胀度及线粒体活力,测定线粒体总ATP酶、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性,以及线粒休一氧化氮(NO)、丙二醛(MDA)含量:电镜观察缺血后皮层神经元超微结构的改变及L-NA对其影响。结果:在大鼠MCAO后线粒体膜肿胀度增加,线粒体活力下降,线粒体NO、MDA含量明显增加,线粒体总ATP酶、SOD、GSH-Px活性均明显下降:缺血后2h、6h、12h给予L-NA治疗3d与缺血对照组相比NO含量明显下降,缺血后12h治疗组线粒体膜肿胀度、线粒体活力、总ATP酶、SOD、GSH-Px活性均显著升高、MDA含量下降。电镜结果显示脑缺血后皮层神经元水肿,线粒体肿胀、嵴断裂、溶解、消失,且随缺血时间延长损伤加重;缺血后12h给予L-NA治疗能明显改善脑缺血引起的神经元水肿、线粒体肿胀和空泡化。结论:L-NA能明显抑制脑缺血后线粒体NO生成,在缺血早期给予L-NA对缺血性脑损伤无改善作用:缺血后期给予L-NA,能明显降低线粒体膜肿胀程度,改善线粒体能量供应,增强线粒体抗氧化作用及其活力,从而减轻脑缺血损伤。     

线粒体ATP合酶抑制因子(ATPIF1)在能量代谢中的作用

线粒体是真核细胞中动态双层膜结构的细胞器,由外至内可以划分为四个功能区,分别是线粒体外膜(OMM),线粒体膜间隙,线粒体内膜(IMM)和线粒体基质。在线粒体内膜上的复合体V(complex V)即为ATP合酶,其主要功能是合成ATP。实际上,ATP合酶既合成也水解ATP,对细胞ATP水平有双向调节作用。ATP合酶的活性受抑制因子(ATPIF1)的调节。ATPIF1与ATP合酶结合后,对其ATP合成和水解功能进行抑制,从而影响线粒体和细胞内ATP水平。ATPIF1活性受到组氨酸质子化状态和丝氨酸磷酸化修饰的调节。在缺氧,交感神经兴奋和肿瘤等条件下,ATPIF1发挥重要代谢调节作用,但其在代谢紊乱疾病中的作用尚不明确。本文在综述ATPIF1文献的基础上,对其在糖脂代谢紊乱疾病中的作用进行分析及展望。     

生物膜组分对膜功能和膜相变的调控 Ⅱ、膜脂组分对水稻线粒体α-酮戊二酸氧化酶活力的影响

以四种抗冷性不同的水稻芽鞘为材料,分析了它们的线粒体膜脂脂肪酸成分和含量、线粒体α-酮戊二酸氧化酶活力,并在线粒体上添加含油酸酯的吐温80和清洗吐温80之后测定了α-酮戊二酸氧化酶活力的变化。 四种抗冷性不同的水稻种子,其干胚膜脂脂肪酸成分相同,但是它们的脂肪酸不饱和指数(IUFA)有明显差异,这种差异与品种抗冷性成正相关。品种间芽鞘线粒体膜脂脂肪酸成分相同,它们的脂肪酸不饱和指数也有明显差异,与品种抗冷性也成正相关。四个水稻品种的芽鞘线粒体α-酮戊二酸氧化酶活力在10～42℃间存在着两个温度折点,其中低温折点可能与品种抗冷性有关。秈稻“二九青”芽鞘线粒体添加吐温80和清洗吐温80后,线粒体α-酮戊二酸氧化酶活力的温度折点均比对照线粒体低。证明增加膜脂中不饱和脂肪酸能降低膜结合酶活力的温度折点,膜脂脂肪酸不饱和度与膜结合酶活力和水稻抗冷性密切相关。     

酞菁类光敏剂对肝癌细胞线粒体和微粒体的光辐射效应

酞菁(Phthalocyanin,PC)化合物结构类似卟啉,是一种新的光敏剂。它的四个苯环上各取代一个磺酸基成为四磺酸酞菁(phthalocyanine tetrasulfonate, TSPC)。TSPC-30μg/ml合并照光30分钟,肝癌细胞线粒体ATP酶和微粒体G-6-P酶明显受抑,对线粒体单胺氧化酶(MAO)没有明显影响。在上述剂量和照光条件下,线粒体和微粒体膜蛋白巯基含量显著减少,而膜脂质过氧化产物增多,线粒体膜通透性改变,导致线粒体肿胀。     

A Highlights from MBoC Selection: Role of mitochondrial inner membrane organizing system in protein biogenesis of the mitochondrial outer membrane

Mitochondria contain two membranes, the outer membrane and the inner membrane with folded cristae. The mitochondrial inner membrane organizing system (MINOS) is a large protein complex required for maintaining inner membrane architecture. MINOS interacts with both preprotein transport machineries of the outer membrane, the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). It is unknown, however, whether MINOS plays a role in the biogenesis of outer membrane proteins. We have dissected the interaction of MINOS with TOM and SAM and report that MINOS binds to both translocases independently. MINOS binds to the SAM complex via the conserved polypeptide transport–associated domain of Sam50. Mitochondria lacking mitofilin, the large core subunit of MINOS, are impaired in the biogenesis of β-barrel proteins of the outer membrane, whereas mutant mitochondria lacking any of the other five MINOS subunits import β-barrel proteins in a manner similar to wild-type mitochondria. We show that mitofilin is required at an early stage of β-barrel biogenesis that includes the initial translocation through the TOM complex. We conclude that MINOS interacts with TOM and SAM independently and that the core subunit mitofilin is involved in biogenesis of outer membrane β-barrel proteins.     

大鼠心肌线粒体内、外膜磷脂动态结构的研究

我们以DPH为荧光探针.用毫微秒荧光分光光度计测定了大鼠心肌线粒体及线粒体内、外膜的动态微细结构;用HPLC分析了磷脂组成.实验结果提示.完整线粒体膜流动性主要反映了线粒体外膜的运动状态.线粒体内膜微粘度及磷脂分子摇动角大于外膜,扩散速率小于外膜.除去了蛋白质的线粒体内、外膜磷脂脂质体膜流动性无明显差异.提示线粒体内膜的高微粘度与膜中所含有的多量蛋白有关.     

LOCALIZATION OF THE ENZYMES OF KETOGENESIS IN RAT LIVER MITOCHONDRIA

The localization of the enzymes of ketogenesis in isolated rat liver mitochondria has been investigated. Mitochondrial subfractions were isolated after disruption of this subcellular organelle by (a) hypotonic lysis in water, which permitted the ultracentrifugal separation of the soluble and membranous compartments of the mitochondrion, or by (b) a procedure involving swelling, contraction, and ultrasonic treatment, which permitted the isolation from discontinuous sucrose gradients of subfractions rich in intermembrane space protein, outer membrane, and inner membrane-matrix particles. Two membrane subfractions were invariably present as distinct bands at the lower interface of the discontinuous gradient. The upper of these two bands was found to be a highly purified preparation of outer mitochondrial membrane. Subfractions rich in matrix and in inner membrane were isolated from inner membrane-matrix particles after hypotonic treatment. The content of the various mitochondrial compartments in all subfractions was assessed from their enzymic and electron microscopic characteristics. The ketogenic activity of each subfraction was determined by measuring its capacity to form ketone bodies from acetyl CoA. The activity of this process was markedly enhanced by dithiothreitol. These measurements of ketone body formation, together with assays of individual enzymes of the ketogenic pathway, show that thiolase, HMGCoA synthase, and HMGCoA cleavage enzyme are localized in the matrix of the inner membrane-matrix particles. The rates of ketone body formation indicate that the HMGCoA synthase is the rate-limiting enzyme of the pathway in subfractions of high matrix content. Studies with sodium chloride indicate that a large portion of the HMGCoA synthase, which remains present in membrane subfractions derived from water-treated mitochondria, is bound by ionic interaction to component(s) of the membrane.     

Role of membrane contact sites in protein import into mitochondria

Mitochondria import more than 1,000 different proteins from the cytosol. The proteins are synthesized as precursors on cytosolic ribosomes and are translocated by protein transport machineries of the mitochondrial membranes. Five main pathways for protein import into mitochondria have been identified. Most pathways use the translocase of the outer mitochondrial membrane (TOM) as the entry gate into mitochondria. Depending on specific signals contained in the precursors, the proteins are subsequently transferred to different intramitochondrial translocases. In this article, we discuss the connection between protein import and mitochondrial membrane architecture. Mitochondria possess two membranes. It is a long‐standing question how contact sites between outer and inner membranes are formed and which role the contact sites play in the translocation of precursor proteins. A major translocation contact site is formed between the TOM complex and the presequence translocase of the inner membrane (TIM23 complex), promoting transfer of presequence‐carrying preproteins to the mitochondrial inner membrane and matrix. Recent findings led to the identification of contact sites that involve the mitochondrial contact site and cristae organizing system (MICOS) of the inner membrane. MICOS plays a dual role. It is crucial for maintaining the inner membrane cristae architecture and forms contacts sites to the outer membrane that promote translocation of precursor proteins into the intermembrane space and outer membrane of mitochondria. The view is emerging that the mitochondrial protein translocases do not function as independent units, but are embedded in a network of interactions with machineries that control mitochondrial activity and architecture.     

ENZYMATIC PROPERTIES OF THE INNER AND OUTER MEMBRANES OF RAT LIVER MITOCHONDRIA

Treatment of rat liver mitochondria with digitonin followed by differential centrifugation was used to resolve the intramitochondrial localization of both soluble and particulate enzymes. Rat liver mitochondria were separated into three fractions: inner membrane plus matrix, outer membrane, and a soluble fraction containing enzymes localized between the membranes plus some solublized outer membrane. Monoamine oxidase, kynurenine hydroxylase, and rotenone-insensitive NADH-cytochrome c reductase were found primarily in the outer membrane fraction. Succinate-cytochrome c reductase, succinate dehydrogenase, cytochrome oxidase, β-hydroxybutyrate dehydrogenase, α-ketoglutarate dehydrogenase, lipoamide dehydrogenase, NAD- and NADH-isocitrate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase, and ornithine transcarbamoylase were found in the inner membrane-matrix fraction. Nucleoside diphosphokinase was found in both the outer membrane and soluble fractions; this suggests a dual localization. Adenylate kinase was found entirely in the soluble fraction and was released at a lower digitonin concentration than was the outer membrane; this suggests that this enzyme is localized between the two membranes. The inner membrane-matrix fraction was separated into inner membrane and matrix by treatment with the nonionic detergent Lubrol, and this separation was used as a basis for calculating the relative protein content of the mitochondrial components. The inner membrane-matrix fraction retained a high degree of morphological and biochemical integrity and exhibited a high respiratory rate and respiratory control when assayed in a sucrose-mannitol medium containing EDTA.     

THE SUBMITOCHONDRIAL LOCALIZATION OF MONOAMINE OXIDASE : An Enzymatic Marker for the Outer Membrane of Rat Liver Mitochondria

Controlled osmotic lysis (water-washing) of rat liver mitochondria results in a mixed population of small vesicles derived mainly from the outer mitochondrial membrane and of larger bodies containing a few cristae derived from the inner membrane. These elements have been separated on Ficoll and sucrose gradients. The small vesicles were rich in monoamine oxidase, and the large bodies were rich in cytochrome oxidase. Separation of the inner and outer membranes has also been accomplished by treating mitochondria with digitonin in an isotonic medium and fractionating the treated mitochondria by differential centrifugation. Treatment with low digitonin concentrations released monoamine oxidase activity from low speed mitochondrial pellets, and this release of enzymatic activity was correlated with the loss of the outer membrane as seen in the electron microscope. The low speed mitochondrial pellet contained most of the cytochrome oxidase and malate dehydrogenase activities of the intact mitochondria, while the monoamine oxidase activity could be recovered in the form of small vesicles by high speed centrifugation of the low speed supernatant. The results indicate that monoamine oxidase is found only in the outer mitochondrial membrane and that cytochrome oxidase is found only in the inner membrane. Digitonin treatment released more monoamine oxidase than cytochrome oxidase from sonic particles, thus indicating that digitonin preferentially degrades the outer mitochondrial membrane.     

Submitochondrial localization of associated mu-calpain and calpastatin

Recently, we have reported the presence of calpain-calpastatin system in mitochondria of bovine pulmonary smooth muscle [P. Kar, T. Chakraborti, S. Roy, R. Choudhury, S. Chakraborti, Arch. Biochem. Biophys. 466 (2007) 290-299]. Herein, we report its localization in the mitochondria. Immunoblot, immunoelectron microscopy and casein zymographic studies suggest that μ-calpain and calpastatin are present in the inner mitochondrial membrane; but not in the outer mitochondrial membrane or in the inter membrane space or in the matrix of the mitochondria. Co-immunoprecipitation studies suggest that μ-calpain-calpastatin is associated in the inner mitochondrial membrane. Additionally, the proteinase K and sodium carbonate treatments of the mitoplasts revealed that μ-calpain is integrally and calpastatin is peripherally embedded to the outer surface of inner mitochondrial membrane. These studies indicate that an association between μ-calpain and calpastatin occurs in the inner membrane towards the inter membrane space of the mitochondria, which provides better insight about the protease regulation towards initiation of apoptotic processes mediated by mitochondria.     

Protein translocation pathways of the mitochondrion

The biogenesis of mitochondria depends on the coordinated import of precursor proteins from the cytosol coupled with the export of mitochondrially coded proteins from the matrix to the inner membrane. The mitochondria contain an elaborate network of protein translocases in the outer and inner membrane along with a battery of chaperones and processing enzymes in the matrix and intermembrane space to mediate protein translocation. A mitochondrial protein, often with an amino-terminal targeting sequence, is escorted through the cytosol by chaperones to the TOM complex (translocase of the outer membrane). After crossing the outer membrane, the import pathway diverges; however, one of two TIM complexes (translocase of inner membrane) is generally utilized. This review is focused on the later stages of protein import after the outer membrane has been crossed. An accompanying paper by Lithgow reviews the early stages of protein translocation.     

Mitochondrial steroid metabolism in the inner and outer zones of the guinea-pig adrenal cortex

Previous investigations have demonstrated that cells isolated from the outer zone (zona fasciculata + zona glomerulosa) of the guinea-pig adrenal cortex produce far more cortisol than those from the inner zone (zona reticularis). Studies were carried out to compare mitochondrial steroid metabolism in the two zones. Protein and cytochrome P-450 concentrations were similar in outer and inner zone mitochondria. However, the rate of 11 beta-hydroxylation was significantly greater in the outer zone despite the fact that substrates for 11 beta-hydroxylation (11-deoxycortisol, 11-deoxycorticosterone) produced larger type I spectral changes in inner zone mitochondria. The apparent affinities of 11-deoxycortisol and 11-deoxycorticosterone for mitochondrial cytochrome(s) P-450 were similar in the two zones. In both inner and outer zone mitochondria, 11 beta-hydroxylation was inhibited by metyrapone but unaffected by aminoglutethimide. Cholesterol sidechain cleavage activity, measured as the rate of conversion of endogenous cholesterol to pregnenolone, was far greater in outer than inner zone mitochondria. Addition of exogenous cholesterol or 25-hydroxycholesterol to the mitochondrial preparations did not affect pregnenolone production in either zone. Addition of pregnenolone to outer zone mitochondria produced a reverse type I spectral change (delta A 420-390 nm), suggesting displacement of endogenous cholesterol from cytochrome P-450. In inner zone mitochondria, pregnenolone induced a difference spectrum (delta A 425-410 nm) similar to the reduced vs oxidized cytochrome b5 spectrum. A b5-like cytochrome was found to be present in the mitochondrial preparations. Prior reduction of the cytochrome with NADH eliminated the pregnenolone-induced spectral change in inner zone mitochondria but had no effect in outer zone preparations. The results suggest that differences in mitochondrial steroid metabolism between the inner and outer adrenocortical zones account in part for the differences in cortisol production by cells in each zone.     

Effects of lipids on mitochondrial functions

Mitochondria contain two membranes: the outer and inner membrane. Whereas the outer membrane is particularly enriched in phospholipids, the inner membrane has an unusual high protein content and forms large invaginations termed cristae. The proper phospholipid composition of the membranes is crucial for mitochondrial functions. Phospholipids affect activity, biogenesis and stability of protein complexes including protein translocases and respiratory chain supercomplexes. Negatively charged phospholipids such as cardiolipin are important for the architecture of the membranes and recruit soluble factors to the membranes to support mitochondrial dynamics. Thus, phospholipids not only form the hydrophobic core of biological membranes that surround mitochondria, but also create a specific environment to promote functions of various protein machineries. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.