Free and membrane-bound ribosomes and NADPH-cytochrome C reductase activity in the liver cells of protein-fed and protein-deprived rats.

Rats were starved for 7 days or fed a protein-free or a 25% casein diet for 7 or 14 days. Free and total ribosomes were prepared from the liver. A determination of the ratio of mg RNA of ribosomes to mg DNA of the total homogenate was made. In starved rats, RNA of free and membrane-bound ribosomes decreased to the same extent. In rats fed a protein-free diet only mg RNA of membrane-bound ribosomes decreased significantly, and after 14 days the ratio of RNA of free to total ribosomes was increased. NADPH-cytochrome c reductase activity in the liver decreased per mg DNA in protein deprivation but was unchanged per mg RNA of membrane-bound ribosomes.