The Role of Cytoplasmic Membranes in Controlling the Transport of Nuclear Messenger RNA and Initiation of Protein Synthesis

Three different classes of poly(A)-containing RNA have been identified in the yeast system. They have been characterized by their kinetics of labeling, by their localization in the nuclear, membranous, and soluble cytoplasmic fractions, and by their size. The evidence indicates that the membrane-bound poly(A)-containing RNA is a product of the nuclear poly(A)-containing RNA and is the precursor of the polysomal poly(A)-containing RNA. In addition, it has been demonstrated that transport of mRNA is coupled with protein synthesis.