Studies on the deposition of plant ferritin as influenced by iron supply to iron-deficient beans

Mature plants can be induced to increase their store of ferritin (phytoferritin) when ferric iron is supplied to iron-deficient bean (Phaseolus vulgaris). The ferritin particles (50-60 Å in diameter) are often deposited in well ordered, "crystalline" arrays. The plant ferritin is always located within the stroma part of thylakoid-free areas in the plastids. Plastids from control plants do not exhibit such electron dense particles. It appears that iron stimulates the production of the protein and becomes the central core of the plant ferritin molecule. Acrylamide gel electrophoresis indicates that plant ferritin, like mammalian ferritin, is a heterogeneous protein. The electrophoretic pattern shows two main bands, each containing iron and protein. By comparison, animal ferritin shows three bands. Both ferritins have identical appearance in the electron microscope.