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@ARTICLE{Nouri:823899,
author = {Nouri, Kazem and Fansa, Eyad K. and Amin, Ehsan and
Dvorsky, Radovan and Gremer, Lothar and Willbold, Dieter and
Schmitt, Lutz and Timson, David J. and Ahmadian, Mohammad
R.},
title = {{IQGAP}1 interaction with {RHO} family proteins revisited:
{K}inetic and equilibrium evidence for multiple distinct
binding sites},
journal = {The journal of biological chemistry},
volume = {291},
issn = {0021-9258},
address = {Bethesda, Md.},
publisher = {Soc.},
reportid = {FZJ-2016-06531},
pages = {26364-26376},
year = {2016},
abstract = {IQ motif-containing GTPase activating protein 1 (IQGAP1)
plays a central role in the physical assembly of relevant
signaling networks that are responsible for various cellular
processes, including cell adhesion, polarity and
transmigration. The RHO family proteins CDC42 and RAC1, have
been shown to mainly interact with the GAPrelated domain
(GRD) of IQGAP1. However, the role of its RASGAP C-terminal
(RGCT) and C-terminal (CT) domains in the interactions with
RHO proteins has remained obscure. Here, we demonstrate that
IQGAP1 interactions with RHO proteins underly a
multiple-step binding mechanism: (i) a high-affinity,
GTPdependent binding of RGCT to the switch regions of CDC42
or RAC1, and (ii) a very low-affinity binding of GRD and CT
adjacent to the switch regions. These data were confirmed by
phosphomimetic mutation of serine 1443 to glutamate within
RGCT, which led to a significant reduction of IQGAP1
affinity for CDC42 and RAC1, clearly disclosing the critical
role of RGCT for these interactions. Unlike CDC42, an
extremely low affinity was determined for the RAC1-GRD
interaction, suggesting that the molecular nature of IQGAP1
interaction with CDC42 partially differs from that of RAC1.
Our study provides new insights into the interaction
characteristics of IQGAP1 with RHO family proteins and
highlights the complementary importance of kinetic and
equilibrium analyses. We propose that the ability of IQGAP1
to interact with RHO proteins is based on a multiple-step
binding process, which is a prerequisite for the dynamic
functions of IQGAP1 as a scaffolding protein and a critical
mechanism in temporal regulation and integration of
IQGAP1-mediated cellular responses.},
cin = {ICS-6},
ddc = {570},
cid = {I:(DE-Juel1)ICS-6-20110106},
pnm = {551 - Functional Macromolecules and Complexes (POF3-551)},
pid = {G:(DE-HGF)POF3-551},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000391568200011},
pubmed = {pmid:27815503},
doi = {10.1074/jbc.M116.752121},
url = {https://juser.fz-juelich.de/record/823899},
}