Ran stimulates spindle assembly by altering microtubule dynamics and the balance of motor activities.
The guanosine tri-phosphatase Ran stimulates assembly of microtubule spindles. However, it is not known what aspects of the microtubule cytoskeleton are subject to regulation by Ran in mitosis. Here we show that Ran-GTP stimulates microtubule assembly by increasing the rescue frequency of microtubules three- to eightfold. In addition to changing microtubule dynamics, Ran-GTP also alters the balance of motor activities, partly as a result of an increase in the amount of motile Eg5, a plus-end-directed microtubule motor that is essential for spindle formation. Thus, Ran regulates multiple processes that are involved in spindle assembly.
Howard Hughes Medical Institute, Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21210, USA.
A
A
Wilde
S B
SB
Lizarraga
L
L
Zhang
C
C
Wiese
N R
NR
Gliksman
C E
CE
Walczak
Y
Y
Zheng
D000818:Animals; D002843:Chromatin / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D016547:Kinesins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000378:metabolism*; D009865:Oocytes / Q000737:chemistry / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D017231:Proto-Oncogene Proteins c-mos / Q000494:pharmacology; D008941:Spindle Apparatus / Q000187:drug effects / Q000502:physiology*; D029867:Xenopus Proteins; D014982:Xenopus laevis; D020931:ran GTP-Binding Protein / Q000378:metabolism*
D002843:Chromatin; C088335:KIF11 protein, Xenopus; D020409:Molecular Motor Proteins; D029867:Xenopus Proteins; D017231:Proto-Oncogene Proteins c-mos; D016547:Kinesins; D020931:ran GTP-Binding Protein; D017239:Paclitaxel; D004121:Dimethyl Sulfoxide