Ultrastructural Study of Rac1 and Its Effectors beneath the Substratum-Facing Membrane

Cell Structure and Function

Mai Kakeno³  Jiro Usukura¹  Takashi Watanabe²  Kozo Kaibuchi³  Shujie Wang³ 

[1] EcoTopia Science Institute, Nagoya University;Institute for Advanced Research, Nagoya University;Department of Cell Pharmacology, Graduate School of Medicine, Nagoya University

关键词: Rac1;    IQGAP1;    Sra-1;    membrane cytoskeleton;    electron microscopy;   

DOI  :  10.1247/csf.08006

学科分类：分子生物学，细胞生物学和基因

来源: Japan Society for Cell Biology

【 摘 要 】

References(29)Cited-By(2)The cytoskeletal architecture and adhesion apparatus are tightly controlled during embryogenesis, tissue development, and carcinogenesis. The Rho family GTPases play central roles in regulation of the cytoskeleton and adhesions. Rac1, one of the Rho family GTPases, appears to be activated at the plasma membrane and exert its functions through its effectors. However, where Rac1 and its effectors function at the molecular level remains to be determined. In this study, we examined the molecular organization on the cytoplasmic surface of the substratum-facing plasma membrane, focusing on Rac1 and its effectors, IQGAP1 and Sra-1, by electron microscopy. We employed deep-etch immunoreplica methods to observe the membrane cytoskeletal architecture while determining molecular locations. Beneath the plasma membrane, Rac1 and its effectors showed similar, but distinct, destinations. Rac1 localized on the membrane and associated with the membrane cytoskeleton. IQGAP1 predominantly localized beside actin filaments and occasionally near microtubules together with Rac1. On the other hand, Sra-1 localized at actin filaments, microtubules, and the plasma membrane. Sra-1 colabeled with Rac1 was mainly found at the membrane and actin filaments. These results suggest that IQGAP1 and Sra-1 colocalize with Rac1 at distinct places, including the plasma membrane and cytoskeletal architecture, for their specific functions.

【 授权许可】

Unknown