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 RIS Download
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