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Sci. Signal., 29 November 2011
Vol. 4, Issue 201, p. rs13
[DOI: 10.1126/scisignal.2002189]

RESEARCH RESOURCES

SH3 Domain–Based Phototrapping in Living Cells Reveals Rho Family GAP Signaling Complexes

Hirokazu Okada1, Akiyoshi Uezu1, Frank M. Mason1, Erik J. Soderblom2, M. Arthur Moseley III2, and Scott H. Soderling1*

1 Department of Cell Biology, Duke University Medical School, Durham, NC 27710, USA.
2 Institute for Genome Science & Policy Proteomics Core Facility, Duke University Medical School, Durham, NC 27710, USA.

Abstract: Rho family GAPs [guanosine triphosphatase (GTPase) activating proteins] negatively regulate Rho family GTPase activity and therefore modulate signaling events that control cytoskeletal dynamics. The spatial distribution of these GAPs and their specificity toward individual GTPases are controlled by their interactions with various proteins within signaling complexes. These interactions are likely mediated through the Src homology 3 (SH3) domain, which is abundant in the Rho family GAP proteome and exhibits a micromolar binding affinity, enabling the Rho family GAPs to participate in transient interactions with multiple binding partners. To capture these elusive GAP signaling complexes in situ, we developed a domain-based proteomics approach, starting with in vivo phototrapping of SH3 domain–binding proteins and the mass spectrometry identification of associated proteins for nine representative Rho family GAPs. After the selection of candidate binding proteins by cluster analysis, we performed peptide array–based high-throughput in vitro binding assays to confirm the direct interactions and map the SH3 domain–binding sequences. We thereby identified 54 SH3-mediated binding interactions (including 51 previously unidentified ones) for nine Rho family GAPs. We constructed Rho family GAP interactomes that provided insight into the functions of these GAPs. We further characterized one of the predicted functions for the Rac-specific GAP WRP and identified a role for WRP in mediating clustering of the postsynaptic scaffolding protein gephyrin and the GABAA ({gamma}-aminobutyric acid type A) receptor at inhibitory synapses.

* To whom correspondence should be addressed. E-mail: s.soderling{at}cellbio.duke.edu

Citation: H. Okada, A. Uezu, F. M. Mason, E. J. Soderblom, M. A. Moseley, III, S. H. Soderling, SH3 Domain–Based Phototrapping in Living Cells Reveals Rho Family GAP Signaling Complexes. Sci. Signal. 4, rs13 (2011).

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Modified SH2 domain to phototrap and identify phosphotyrosine proteins from subcellular sites within cells.
A. Uezu, H. Okada, H. Murakoshi, C. D. del Vescovo, R. Yasuda, D. Diviani, and S. H. Soderling (2012)
PNAS 109, E2929-E2938
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