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Updated: Jul 16, 2026

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
Published on: October 8, 2015
Stimulation of microtubule aster formation and spindle assembly by the small GTPase Ran
1Carnegie Institution of Washington, Department of Embryology, Baltimore, MD 21210, USA.
Abstract:
Ran, a small guanosine triphosphatase, is suggested to have additional functions beyond its well-characterized role in nuclear trafficking. Guanosine triphosphate-bound Ran, but not guanosine diphosphate-bound Ran, stimulated polymerization of astral microtubules from centrosomes assembled on Xenopus sperm. Moreover, a Ran allele with a mutation in the effector domain (RanL43E) induced the formation of microtubule asters and spindle assembly, in the absence of sperm nuclei, in a gammaTuRC (gamma-tubulin ring complex)- and XMAP215 (Xenopus microtubule associated protein)-dependent manner. Therefore, Ran could be a key signaling molecule regulating microtubule polymerization during mitosis.
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