Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
J Biol Chem. 2000 Jun 9;275(23):17848-56.

Phosphorylation of the nuclear transport machinery down-regulates nuclear protein import in vitro.

Author information

  • 1Departments of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.

Abstract

We have examined whether signal-mediated nucleocytoplasmic transport can be regulated by phosphorylation of the nuclear transport machinery. Using digitonin-permeabilized cell assays to measure nuclear import and export, we found that the phosphatase inhibitors okadaic acid and microcystin inhibit transport mediated by the import receptors importin beta and transportin, but not by the export receptor CRM1. Several lines of evidence, including the finding that transport inhibition is partially reversed by the broad specificity protein kinase inhibitor staurosporine, indicate that transport inhibition is due to elevated phosphorylation of a component of the nuclear transport machinery. The kinases and phosphatases involved in this regulation are present in the permeabilized cells. A phosphorylation-sensitive component of the nuclear transport machinery also is present in permeabilized cells and is most likely a component of the nuclear pore complex. Substrate binding by the importin alpha.beta complex and the association of the complex with the nucleoporins Nup358/RanBP2 and Nup153 are not affected by phosphatase inhibitors, suggesting that transport inhibition by protein phosphorylation does not involve these steps. These results suggest that cells have mechanisms to negatively regulate entire nuclear transport pathways, thus providing a means to globally control cellular activity through effects on nucleocytoplasmic trafficking.

PMID:
10749866
[PubMed - indexed for MEDLINE]
Free full text

LinkOut - more resources

Full Text Sources

Molecular Biology Databases

Miscellaneous

PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire
    Loading ...
    Write to the Help Desk