铁硫(Fe-S)蛋白定位于哺乳动物细胞的细胞质、细胞核和线粒体(详见Stemmler et al. 2010, Rouault 2012, Bandyopadhyay et al. 2008, Lill 2009, Lill et al. 2012)。线粒体基质中Fe-S蛋白的生物发生涉及到铁硫簇(ISC)组装机制。亚铁通过Mitoferrin-1 (SLC25A37)和Mitoferrin-2 (SLC25A28)穿过线粒体内膜进入线粒体基质。(红细胞中含有丰富的丝裂铁蛋白1，而丝裂铁蛋白2则普遍存在。)Frataxin在线粒体基质中结合亚铁。与ISD11亚复合物中的半胱氨酸脱硫酶NFS1通过将半胱氨酸转化为丙氨酸和形成过硫化物提供硫，过硫化物用于在支架蛋白ISCU上形成簇。NFS1和ISD11之间的相互作用是脱硫酶活性的必要条件。Frataxin与包含NFS1, ISD11和ISCU的复合物结合，并被提议作为ISCU的铁供体或作为一个变构开关，激活硫转移和Fe-S簇组装(Tsai和Barondeau, 2010)。簇的形成还涉及到电子传递链、铁还蛋白还原酶和铁还蛋白。ISCU最初形成包含2个铁原子和2个硫原子的团簇([2Fe-2S]团簇)。 They are released by the function of HSP70-HSC20 chaperones and the monothiol glutaredoxin GLRX5 and used for assembly of [2Fe-2S] proteins. Assembly of larger clusters such as [4Fe-4S] clusters may involve the function of ISCA1, ISCA2, and IBA57. The clusters are transferred to apo-enzymes such as the respiratory complexes, aconitase, and lipoate synthase through dedicated targeting factors such as IND1, NFU1, and BOLA3.