Molecular and Cellular Biochemistry

, 318:43

IQ motif selectivity in human IQGAP1: binding of myosin essential light chain and S100B

Authors

  • Sevvel Pathmanathan
    • Medical Biology Centre, School of Biological SciencesQueen’s University Belfast
  • Sarah F. Elliott
    • Medical Biology Centre, School of Biological SciencesQueen’s University Belfast
  • Sara McSwiggen
    • Medical Biology Centre, School of Biological SciencesQueen’s University Belfast
  • Brett Greer
    • Medical Biology Centre, School of Biological SciencesQueen’s University Belfast
  • Pat Harriott
    • Medical Biology Centre, School of Biological SciencesQueen’s University Belfast
  • G. Brent Irvine
    • School of Medicine & DentistryQueen’s University Belfast
    • Medical Biology Centre, School of Biological SciencesQueen’s University Belfast
Article

DOI: 10.1007/s11010-008-9855-9

Cite this article as:
Pathmanathan, S., Elliott, S.F., McSwiggen, S. et al. Mol Cell Biochem (2008) 318: 43. doi:10.1007/s11010-008-9855-9

Abstract

IQGAPs are cytoskeletal scaffolding proteins which link signalling pathways to the reorganisation of actin and microtubules. Human IQGAP1 has four IQ motifs each of which binds to calmodulin. The same region has been implicated in binding to two calmodulin-like proteins, the myosin essential light chain Mlc1sa and the calcium and zinc ion binding protein S100B. Using synthetic peptides corresponding to the four IQ motifs of human IQGAP1, we showed by native gel electrophoresis that only the first IQ motif interacts with Mlc1sa. This IQ motif, and also the fourth, interacts with the budding yeast myosin essential light chain Mlc1p. The first and second IQ motifs interact with S100B in the presence of calcium ions. This clearly establishes that S100B can interact with its targets through IQ motifs in addition to interacting via previously reported sequences. These results are discussed in terms of the function of IQGAP1 and IQ motif recognition.

Keywords

Calcium ionsCytoskeletonEF-handIQ motifMlc1saNative gel

Abbreviations

APC

Adenomatous polyposis coli

DIEA

N,N-diisopropylethylamine

FhCaM2

Fasciola hepatica type 2 calmodulin

Fmoc

9-Fluorenylmethoxycarbonyl

HATU

2-(1H-7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyl uronium hexafluorophosphate methanaminium

IQ1, IQ2, IQ3, IQ4

The first, second, third and fourth IQ motifs (as numbered from the N-terminus), respectively, of human IQGAP1

Kd,app

The apparent disassociation constant under the conditions of native gel electrophoresis

LB

Luria-Bertani

TFA

Trifluoroacetic acid

VEGFR2

Vascular endothelial growth factor receptor

Copyright information

© Springer Science+Business Media, LLC. 2008