Signal-mediated nuclear export pathways of proteins and RNAs

Although it has been known for several years that most nuclear-encoded RNAs and some proteins can be exported from the nucleus to the cytoplasm, the molecular mechanisms of these transport processes have been poorly understood. Recently, signals that can induce the rapid and active nuclear export of macromolecules have been identified in the HIV-1 Rev protein, the inhibitor of cAMP-dependent protein kinase (PKI) and the hnRNP A1 protein. Thus, nuclear export appears to be mechanistically similar to nuclear import in that it requires specific signal-receptor systems.