The assembly of mitochondrial c-type cytochromes by System III

蛋白质是复杂的生物分子，对所有活细胞的结构和功能至关重要。为了使它们的功能多样化，蛋白质使用称为辅助因子的额外分子，其中有许多类型。血红素就是这样一种辅助因子；它是一种中心有铁原子的有机化学物质，在不同的细胞过程中具有许多基本功能。许多含有血红素的蛋白质在细胞中形成后，会经历一个过程，在蛋白质和血红素之间形成键；它们被称为细胞色素c，在呼吸和涉及电子转移的反应中是必不可少的。在动物细胞中有两种c型细胞色素分子，它们都存在于线粒体中。这些细胞色素在支撑线粒体作为细胞动力源的作用上起着关键作用。此外，在某些条件下，这些细胞色素c中的一种可以从线粒体中释放出来，作为程序性细胞死亡过程的触发器。在其他情况下，血红素与蛋白质结合而不形成键，例如在血红蛋白中，血红蛋白利用血红素结合血液中的氧气。在血红素辅助因子与细胞色素结合的情况下，需要其他蛋白质来协助这个不是自发的反应。在动物中，单一蛋白质加速血红素与蛋白质的共价附着，从而产生细胞色素c。我们提出的研究旨在利用各种实验方法和技术了解这种蛋白质的功能。为了完成对构成生命的基本生化反应的描述，理解制造细胞色素c的过程作为一个基本的和中心的生物过程也很重要。

Proteins are complex biomolecules that are essential to the structure and function of all living cells. In order to diversify their functions, proteins use additional molecules called cofactors, of which there are many types. Heme is one such cofactor; it is an organic chemical with an iron atom in the centre and has many essential functions in different cellular processes. Many proteins that contain heme undergo a process after they are made in the cell in which bonds are formed between the protein and the heme; these are called cytochromes c and are essential in respiration and in reactions that involve the transfer of electrons. In animal cells there are two c-type cytochrome molecules which are both found in the mitochondria. These cytochromes play a key role underpinning the mitochondrion's role as the powerhouse of the cell. Additionally, one of these cytochromes c can be released from the mitochondrion under certain conditions as a trigger for the process of programmed cell death. In other cases, heme associates with proteins without forming bonds with them, for example in hemoglobin, which uses the heme to bind oxygen in blood. In the case where the heme cofactor becomes bonded to the cytochrome, other proteins are needed to assist in this reaction, which is not spontaneous. In animals a single protein speeds up the covalent attachment of heme to protein to give a cytochrome c. Our proposed research seeks to understand how this protein functions, using a variety of experimental approaches and techniques. It is also important to understand the process of making cytochromes c as a fundamental and central biological process, in order to complete a description of the essential biochemical reactions that constitute life.