The labeling of polysomes and rough microsomal membranes by 5-fluoroorotic acid

Using [2- 14 C]fluoroorotic acid for the selective labeling of rat liver messenger RNA, strikingly different levels of radioactivity appeared in the bound and free classes of polysomes (free > bound, ∼ 3:1) well-washed rough microsomal membrane preparations, contained 5X more radioactivity than their own bound polysomes.