Importins role

There are some transport pathways for mRNA export which do not require an importin/3 family member. Mex67/TAP is a factor with a direct role in mRNA export (Strasser and Hurt, 2000 Stutz et al., 2000 Nakielny and Dreyfuss, 1999). Mex67/TAP binds RNA and Nups and has the ability to undergo nucleocytoplasmic shuttling. Another factor might be involved (Hodge et al., 1999). How the actions of these factors are coordinated to mediate mRNA export is presently unknown. Once recognized by the export machinery, RNAs must transverse the nuclear pore. 

J.F. Reilly, and P.A. Maher, Importin beta-mediated nuclear import of fibroblast growth factor receptor role in cell proliferation, J Cell Biol 152, 1307-1312 (2001). 

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