Journal of Cell Science 116, e402-e402 (2003)
Copyright © 2003 The Company of Biologists Limited
Exporting RNA
Nuclear export — and import — of proteins generally involves
the karyopherin family of transport receptors and depends on the gradient of
GTP-bound Ran set up across the nuclear envelope. But RNAs that function in
the cytoplasm must also be exported. Do they use the same machinery? In a
Commentary on p. 587, Bryan
Cullen reviews work that has shown that in fact a variety of RNA export
mechanisms exist — some karyopherin based, some not. Early analyses of
retroviral RNA export indicated that these RNAs bind to adaptor proteins (e.g.
HIV-1 Rev) that interact with the karyopherin Crm1, and subsequent work has
revealed that Crm1 mediates Ran-dependent export of adaptor-bound snRNAs,
rRNAs and certain mRNAs. tRNA export also seems to be Ran dependent, relying
on the karyopherin Exp-t, which binds directly to tRNAs. Export of most mRNAs,
by contrast, does not involve karyopherins or Ran. Instead these RNAs bind to
a protein termed Tap (Mex67p in yeast), which, together with Nxt (Mtr2p),
binds directly to nuclear pore components. A common feature of all these
mechanisms, however, is the assembly of RNA into RNP complexes, which probably
acts as an important proofreading mechanism.
Related articles in JCS:
- Nuclear RNA export
- Bryan R. Cullen
JCS 2003 116: 587-597.
[Abstract]
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