p140Sra-1 (specifically Rac1-associated protein) is a novel specific target for Rac1 small GTPase

Kenta Kobayashi, Shinya Kuroda, Masaki Fukata, Tomoko Nakamura, Takahiro Nagase, Nobuo Nomura, Yoshiharu Matsuura, Nobuko Yoshida-Kubomura, Akihiro Iwamatsu, Kozo Kaibuchi

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Abstract

Rac1 small GTPase plays pivotal roles in various cell functions such as cell morphology, cell polarity, and cell proliferation. We have previously identified IQGAP1 from bovine brain cytosol as a target for Rac1 by an affinity purification method. By using the same method, we purified a specifically Rac1-associated protein with a molecular mass of about 140 kDa (p140) from bovine brain cytosol. This protein interacted with guanosine 5'- (3-O-thio)triphosphate (GTPγS)-glutathione S-transferase (GST)-Rac1 but not with the GDP·GST-Rac1, GTPγS·GST-Cdc42, or GTPγS·GST-RhoA. The amino acid sequences of this protein revealed that p140 is identified as a product of KIAA0068 gene. We denoted this protein as Sra-1 (Specifically Rac1- associated protein). Recombinant Sra-1 interacted with GTPγS·GST-Rac1 and weakly with GDP·Rac1 but not with GST-Cdc42 or GST-RhoA. The N-terminal domain of Sra-1 (1-407 amino acids) was responsible for the interaction with Rac1. Myc-tagged Sra-1 and the deletion mutant capable of interacting with Rac1, but not the mutants unable to bind Rac1, were colocalized with dominant active Rac1(Val-12) and cortical actin filament at the Rac1(Val-12), induced membrane ruffling area in KB cells. Sra-1 was cosedimented with filamentous actin (F-actin), indicating that Sra-1 directly interacts with F-actin. These results suggest that Sra-1 is a novel and specific target for Rac1.

Original languageEnglish
Pages (from-to)291-295
Number of pages5
JournalJournal of Biological Chemistry
Volume273
Issue number1
DOIs
Publication statusPublished - 02-01-1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Kobayashi, K., Kuroda, S., Fukata, M., Nakamura, T., Nagase, T., Nomura, N., Matsuura, Y., Yoshida-Kubomura, N., Iwamatsu, A., & Kaibuchi, K. (1998). p140Sra-1 (specifically Rac1-associated protein) is a novel specific target for Rac1 small GTPase. Journal of Biological Chemistry, 273(1), 291-295. https://doi.org/10.1074/jbc.273.1.291