What makes Ran run?

Changes in the nucleotide state of Ran, a small GTPase, provide the energy that drives transport into the nucleus. But so many proteins affect Ran's status or localization that is has been difficult to work out which, if any, are the key control points. Now, Alicia Smith and Ian Macara (University of Virginia, Charlottesville, VA) and colleagues have coupled real-time measurements of Ran transport with a computational model to come up with an answer.

“There's been a lot of hype about computational biology, but it's actually only useful to address certain types of questions,” says Macara. “This was a compartmental problem, so it was relatively easy to set up the model.” Macara did so with the help of Virtual Cell, a program developed by Leslie Loew and colleagues at the University of Connecticut Health Center, Farmington,...