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J Biol Chem. 2014 Dec 19;289(51):35397-408. doi: 10.1074/jbc.M114.615112. Epub 2014 Oct 20.

Src homology 2 domain containing protein 5 (SH2D5) binds the breakpoint cluster region protein, BCR, and regulates levels of Rac1-GTP.

Author information

1
From the Department of Molecular Genetics, University of Toronto, Ontario M5S1A8, Canada, the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G1X5, Canada, elizabeth.gray@camh.ca.
2
the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G1X5, Canada.
3
the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G1X5, Canada, Sanofi Pasteur, Toronto, Ontario M2R3T4, Canada, and.
4
the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G1X5, Canada, the Max Delbrück Center for Molecular Medicine Berlin-Buch, Robert-Rössle-Strasse 10, 13125 Berlin, Germany.
5
From the Department of Molecular Genetics, University of Toronto, Ontario M5S1A8, Canada, the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G1X5, Canada, gingras@lunenfeld.ca.
6
From the Department of Molecular Genetics, University of Toronto, Ontario M5S1A8, Canada, the Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G1X5, Canada.

Abstract

SH2D5 is a mammalian-specific, uncharacterized adaptor-like protein that contains an N-terminal phosphotyrosine-binding domain and a C-terminal Src homology 2 (SH2) domain. We show that SH2D5 is highly enriched in adult mouse brain, particularly in Purkinjie cells in the cerebellum and the cornu ammonis of the hippocampus. Despite harboring two potential phosphotyrosine (Tyr(P)) recognition domains, SH2D5 binds minimally to Tyr(P) ligands, consistent with the absence of a conserved Tyr(P)-binding arginine residue in the SH2 domain. Immunoprecipitation coupled to mass spectrometry (IP-MS) from cultured cells revealed a prominent association of SH2D5 with breakpoint cluster region protein, a RacGAP that is also highly expressed in brain. This interaction occurred between the phosphotyrosine-binding domain of SH2D5 and an NxxF motif located within the N-terminal region of the breakpoint cluster region. siRNA-mediated depletion of SH2D5 in a neuroblastoma cell line, B35, induced a cell rounding phenotype correlated with low levels of activated Rac1-GTP, suggesting that SH2D5 affects Rac1-GTP levels. Taken together, our data provide the first characterization of the SH2D5 signaling protein.

KEYWORDS:

Adaptor Proteins; BCR Signaling; Mass Spectrometry (MS); PTB Domain; Phosphotyrosine; Ras-related C3 Botulinum Toxin Substrate 1 (Rac1); Rho GTPases; SH2D5 Signaling; Signal Transduction; Src Homology 2 Domain (SH2 Domain)

PMID:
25331951
PMCID:
PMC4271225
DOI:
10.1074/jbc.M114.615112
[Indexed for MEDLINE]
Free PMC Article

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