Calmodulin modulates the interaction between IQGAP1 and Cdc42: Identification of IQGAP1 by nanoelectrospray tandem mass spectrometry

John L. Joyal, Roland S. Annan, Yen Dong Ho, Michael E. Huddleston, Steven A. Carr, Matthew J Hart, David B. Sacks

Research output: Contribution to journalArticle

117 Citations (Scopus)

Abstract

Calmodulin regulates numerous fundamental metabolic pathways by binding to and modulating diverse target proteins. In this study, calmodulin-binding proteins were isolated from normal (Hs578Bst) and malignant (MCF-7) human breast cell lines with calmodulin-Sepharose and analyzed by SDS- polyacrylamide gel electrophoresis. A protein that migrated at approximately 190 kDa bound to calmodulin in the presence of Ca2+ and was the only calmodulin-binding protein detected in the absence of Ca2+. This 190-kDa protein was identified as IQGAP1 by nanoelectrospray mass spectrometry and collision-induced dissociation tandem mass spectrometry. IQGAP1 coimmunoprecipitated with calmodulin from lysates of MCF-7 cells. Moreover, overlay with 125I-calmodulin confirmed that IQGAP1 binds directly to calmodulin. Analysis of the functional effects of the interaction revealed that Ca2+/calmodulin disrupted the binding of purified IQGAP1 to the Ras- related protein Cdc42 in a concentration-dependent manner. These data clearly identify IQGAP1 as the predominant calmodulin-binding protein in Ca2+-free breast cell lysates and reveal that calmodulin modulates the interaction between IQGAP1 and Cdc42.

Original languageEnglish (US)
Pages (from-to)15419-15425
Number of pages7
JournalJournal of Biological Chemistry
Volume272
Issue number24
DOIs
StatePublished - Jun 13 1997
Externally publishedYes

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Calmodulin
Tandem Mass Spectrometry
Mass spectrometry
Calmodulin-Binding Proteins
cdc42 GTP-Binding Protein
Breast
ras Proteins
Proteins
MCF-7 Cells
Metabolic Networks and Pathways
Electrophoresis
Sepharose
Polyacrylamide Gel Electrophoresis
Mass Spectrometry
Cells
Cell Line

ASJC Scopus subject areas

  • Biochemistry

Cite this

Calmodulin modulates the interaction between IQGAP1 and Cdc42 : Identification of IQGAP1 by nanoelectrospray tandem mass spectrometry. / Joyal, John L.; Annan, Roland S.; Ho, Yen Dong; Huddleston, Michael E.; Carr, Steven A.; Hart, Matthew J; Sacks, David B.

In: Journal of Biological Chemistry, Vol. 272, No. 24, 13.06.1997, p. 15419-15425.

Research output: Contribution to journalArticle

Joyal, John L. ; Annan, Roland S. ; Ho, Yen Dong ; Huddleston, Michael E. ; Carr, Steven A. ; Hart, Matthew J ; Sacks, David B. / Calmodulin modulates the interaction between IQGAP1 and Cdc42 : Identification of IQGAP1 by nanoelectrospray tandem mass spectrometry. In: Journal of Biological Chemistry. 1997 ; Vol. 272, No. 24. pp. 15419-15425.
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