Characterization of IQGAP1-Containing Complexes in NK-Like Cells: Evidence for Rac 2 and RACK1 Association during Homotypic Adhesion
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- 作者：Xiaobo Meng ; Oleg Krokhin ; Keding Cheng ; Werner Ens ; John A. Wilkins
- 刊名：Journal of Proteome Research
- 出版年：2007
- 出版时间：February 2007
- 年：2007
- 卷：6
- 期：2
- 页码：744 - 750
- 全文大小：237K
- 年卷期：v.6,no.2(February 2007)
- ISSN：1535-3907
文摘
IQGAP1 is a scaffolding protein that binds to a diverse array of signaling and structural molecules thatare often associated with cell polarization and adhesion. Through interaction with its target proteins,IQGAP1 participates in multiple cellular functions, including Ca2+-calmodulin signaling, definition ofcytoskeletal architecture, regulation of Cdc42 and Rac1 dependent cytoskeletal changes, and controlof E-cadherin mediated intercellular adhesion. These analysis have been largely restricted to cells ofepithelial and fibroblast origin. The present studies were initiated to examine the role of IQGAP1 incellular interactions involving the lymphoid cells. A mass spectrometric based analysis of IQGAP1containing complexes isolated from the human NK-like cell line, YTS, identified several known andnew potential IQGAP1 interaction partners including receptor of activated C kinase 1 (RACK1) and thesmall GTPase, Rac2. Immunofluorescence analysis of YTS cells indicated that a minor component ofIQGAP1 was localized at the cell membrane with the remainder diffusely distributed through out thecytoplasm. However, at sites of cellular contact, there was a marked accumulation of IQGAP1. Stainingfor RACK1 and Rac2 revealed that both of these proteins accumulated these contact sites. Antibody-based studies suggested that a subset of RACK1 was associated in an IQGAP1-containing complex,which prevented recognition of RACK1 by monoclonal antibody. These results suggest that RACK1,Rac2, and IQGAP1 are components of complexes involved in NK cell homotypic adhesion.