Lescure A M, Proudhon D, Pesey H, Ragland M, Theil E C, Briat J F
Laboratoire de Biologie Moléculaire Végétale, Centre National de la Recherche Scientifique (Unité de Recherche Associée 1178), Grenoble, France.
Proc Natl Acad Sci U S A. 1991 Sep 15;88(18):8222-6. doi: 10.1073/pnas.88.18.8222.
Iron-regulated ferritin synthesis in animals is dominated by translational control of stored mRNA; iron-induced transcription of ferritin genes, when it occurs, changes the subunit composition of ferritin mRNA and protein and is coupled to translational control. Ferritins in plants and animals have evolved from a common progenitor, based on the similarity of protein sequence; however, sequence divergence occurs in the C termini; structure prediction suggests that plant ferritin has the E-helix, which, in horse ferritin, forms a large channel at the tetrameric interface. In contemporary plants, a transit peptide is encoded by ferritin mRNA to target the protein to plastids. Iron-regulated synthesis of ferritin in plants and animals appears to be very different since the 50- to 60-fold increases of ferritin protein, previously observed to be induced by iron in cultured soybean cells, is accompanied by an equivalent accumulation of hybridizable ferritin mRNA and by increased transcription of ferritin genes. Ferritin mRNA from iron-induced cells and the constitutive ferritin mRNA from soybean hypocotyls are identical. The iron-induced protein is translocated normally to plastids. Differences in animal ferritin structure coincide with the various iron storage functions (reserve for iron proteins and detoxification). In contrast, the constancy of structure of soybean ferritin, iron-induced and constitutive, coupled with the potential for vacuolar storage of excess iron in plants suggest that rapid synthesis of ferritin from a stored ferritin mRNA may not be needed in plants for detoxification of iron.
动物体内铁调节的铁蛋白合成主要由储存mRNA的翻译控制主导；铁诱导的铁蛋白基因转录（若发生）会改变铁蛋白mRNA和蛋白质的亚基组成，并与翻译控制相关联。基于蛋白质序列的相似性，动植物中的铁蛋白由共同的祖先演化而来；然而，C末端存在序列差异；结构预测表明植物铁蛋白具有E螺旋，而在马铁蛋白中，E螺旋在四聚体界面形成一个大通道。在现代植物中，铁蛋白mRNA编码一个转运肽，将蛋白质靶向到质体。动植物中铁调节的铁蛋白合成似乎非常不同，因为之前在培养的大豆细胞中观察到铁诱导铁蛋白蛋白增加50至60倍时，伴随着可杂交铁蛋白mRNA的等量积累以及铁蛋白基因转录增加。来自铁诱导细胞的铁蛋白mRNA与大豆下胚轴组成型铁蛋白mRNA相同。铁诱导的蛋白质正常转运到质体。动物铁蛋白结构的差异与各种铁储存功能（作为铁蛋白的储备和解毒）相一致。相比之下，大豆铁蛋白（铁诱导型和组成型）结构的稳定性，以及植物中过量铁在液泡中储存的可能性表明，植物可能不需要从储存的铁蛋白mRNA快速合成铁蛋白来解毒铁。
