Ran on tracks--cytoplasmic roles for a nuclear regulator.
The GTPase Ran is best known for its crucial roles in the regulation of nucleocytoplasmic transport in interphase cells and in the organization of the spindle apparatus during mitosis. A flurry of recent reports has now implicated Ran in diverse cytoplasmic events, including trafficking of an ephrin receptor homolog in nematode oocytes, control of neurite outgrowth in Drosophila and mammalian neurons, and retrograde signaling in nerve axons after injury. Striking findings suggest that the guanine-nucleotide state of Ran can be regulated by local translation of the Ran-binding protein RanBP1 in axons, and that an additional Ran-binding protein, RanBP10, can act as a microtubule-binding cytoplasmic guanine-nucleotide exchange factor for Ran (RanGEF) in megakaryocytes. Thus, the Ran GTPase system can act as a spatial regulator of importin-dependent transport and signaling in distal cytoplasm, and as a regulator of cytoskeletal dynamics at sites that are distant from the nucleus.
Yudin
Dmitry
D
Department of Biological Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel.
Fainzilber
Mike
M
D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism; D007399:Interphase / Q000502:physiology; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D016415:Sequence Alignment; D020931:ran GTP-Binding Protein / Q000378:metabolism*
D020662:Guanine Nucleotide Exchange Factors; D008869:Microtubule-Associated Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D020931:ran GTP-Binding Protein