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Rac1 and Cdc42 capture microtubules through IQGAP1 and CLIP-170.

Linkage of microtubules to special cortical regions is essential for cell polarization. CLIP-170 binds to the growing ends of microtubules and plays pivotal roles in orientation. We have found that IQGAP1, an effector of Rac1 and Cdc42, interacts with CLIP-170. In Vero fibroblasts, IQGAP1 localizes at the polarized leading edge. Expression of carboxy-terminal fragment of IQGAP1, which includes the CLIP-170 binding region, delocalizes GFP-CLIP-170 from the tips of microtubules and alters the microtubule array. Activated Rac1/Cdc42, IQGAP1, and CLIP-170 form a tripartite complex. Furthermore, expression of an IQGAP1 mutant defective in Rac1/Cdc42 binding induces multiple leading edges. These results indicate that Rac1/Cdc42 marks special cortical spots where the IQGAP1 and CLIP-170 complex is targeted, leading to a polarized microtubule array and cell polarization.

Pubmed ID: 12110184


  • Fukata M
  • Watanabe T
  • Noritake J
  • Nakagawa M
  • Yamaga M
  • Kuroda S
  • Matsuura Y
  • Iwamatsu A
  • Perez F
  • Kaibuchi K



Publication Data

June 28, 2002

Associated Grants


Mesh Terms

  • Actins
  • Animals
  • COS Cells
  • Carrier Proteins
  • Cattle
  • Cell Polarity
  • Cell Size
  • Cercopithecus aethiops
  • Macromolecular Substances
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins
  • Microtubules
  • Neoplasm Proteins
  • Protein Binding
  • Pseudopodia
  • Vero Cells
  • cdc42 GTP-Binding Protein
  • rac1 GTP-Binding Protein
  • ras GTPase-Activating Proteins