Regulation of plant ferritin synthesis: how and why

Plant ferritins are key iron-storage proteins that share important structur al and functional similarities with animal ferritins. However, specific fea tures characterize plant ferritins, among which are plastid cellular locali zation and transcriptional regulation by iron. Ferritin synthesis is develo pmentally and environmentally controlled, in part through the differential expression of the various members of a small gene family. Furthermore, a st rict requirement for plant ferritin synthesis regulation is attested to by alterations of the photosynthetic apparatus and of iron homeostasis in tran sgenic tobaccos overexpressing these proteins. Plant ferritin gene regulati on appears to consist of a complex interplay of transcriptional and posttra nscriptional mechanisms, involving cellular relays such as plant hormones, oxidative steps and Ser/Thr phosphatase.