Two higher molecular weight forms related to ferritin are synthesizedin vitro by RNA from developing cotyledons and leaves ofPhaseolus vulgaris.

Using RNA from developing cotyledons and leaves of bean two products were synthesizedin vitro, with Mr 31000 and 31500 which are antigenically related to the subunit of phytoferritin (Mr 26500). The relative abundance of the two products is dependent on the type of tissue from which the RNA was derived. Evidence is presented for the assumption that both products are precursors of the phytoferritin subunit. The hypothesis is put forward that different transit sequences direct the phytoferritin subunits to different cell organelles.