FERRITIN IN THE FUNGUS PHYCOMYCES
b'The iron-protein ferritin has been purified from mycelium, sporangiophores, and spores of\\nthe fungus Phycomyces blakesleeanus. It has a protein-to-iron ratio of 5, a sedimentation coefficient\\nof 55S, a buoyant density in CsCI of 1 .82 g/cm3, and the characteristic morphology\\nof ferritin in the electron microscope . Apoferritin prepared from Phycomyces ferritin has a\\nsedimentation coefficient of 18S and consists of subunits of molecular weight 25,000 . In the\\ncytoplasm of Phycomyces, ferritin is located on the surface of lipid droplets (0 .5-2 .0 y in\\ndiameter) where it forms crystalline monolayers which are conspicuous in electron micrographs\\nof sporangiophore thin-sections . Ferritin is found in all developmental stages of\\nPhycomyces but is concentrated in spores . The level of ferritin iron is regulated by the iron\\nlevel in the growth medium, a 50-fold increase occurring on iron-supplemented medium .'