ABSTRACT
Transport of mRNA from the nucleus to the cytoplasm is an ATP-dependent process, which occurs strictly vectorially. The transport from the nucleus to the cytoplasm consists of three steps: release of mRNA from the intranuclear binding site, translocation of mRNA through a nuclear pore complex, and association of the transported mRNA with the cytoplasmic cytoskeleton. Selective transport of a specific mRNA requires the existence of additional factors, which are able to recognize these mRNAs and facilitate their transport through the nuclear pore. To investigate the interaction of Rev protein with the mRNA-translocation machinery different in vitro model systems were used which have proved to be suitable for the study of mRNA transport. Insulin and epidermal growth factor modulate the rate of transport of poly(A)+mRNA by a direct interaction with the nucleocytoplasmic translocation system. The cytoplasm contains proteins that stimulate mRNA transport. The amount of mRNA transported from nuclei per unit time is markedly reduced during aging.
