Nuclear export signal sequence

Expoitins are transport receptors at the nuclear pore complex needed for the selective export of proteins from the nucleus into the cytoplasm. They recognize nuclear export signal sequences of cargo proteins. 

Bogerd, H.P., Fridell, R.A., Benson, R.E. and Cullen, B.R. (1996) Protein sequence requirements for function of the human T-cell leukemia virus type 1 Rex nuclear export signal delineated by an in vivo randomization-selection assay. Mol. Cell. Biol., 16, 4207-A214. 

Proteins Imported to or exported from the nucleus contain a specific amino acid sequence that functions as a nuclear-localization signal (NLS) or a nuclear-export signal (NFS). Nucleus-restricted proteins contain an NLS but not an NES, whereas proteins that shuttle between the nucleus and cytoplasm contain both signals. 

RNAs are transported from the nucleus to the cytoplasm as ribonucleoproteins, which are targeted for export by a specific amino acid sequence called the nuclear export signal. The nucleoprotein forms a complex with additional proteins called exportins and with Ran. This complex is transported through the pore to the cytoplasm, where RanGAP activates hydrolysis of the bound GTP. In the absence of GTP, the complex dissociates with the release of RNA into the cytoplasm, and the exportins and Ran are transported back to the nucleus. 

Figure 4. Schematic representation of the human PARG gene exon structure and of three PARG isoforms that result from translation of PARG mRNAsplice variants. Abbreviations used are NLS, nuclear localization signal, NES, nuclear export signal, MTS, mitochondrial targeting sequence.

He, X. P., Bataille, N., and Fried, H. M. (1994). Nuclear export of signal recognition particle RNA is a facilitated process that involves the Alu sequence domain. J. Cell Sci. 107,903-912. 

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