The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade.

The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Research Abstract Details 

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The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Abstract Text:

Dan Baird,Qiyu Feng,Richard A Cerione,

BACKGROUND: Cloned-out of library-2 (Cool-2)/PAK-interactive exchange factor (alpha-Pix) was identified through its ability to bind the Cdc42/Rac target p21-activated kinase (PAK) and has been implicated in certain forms of X-linked mental retardation as well as in growth factor- and chemoattractant-coupled signaling pathways. We recently found that the dimeric form of Cool-2 is a specific guanine nucleotide exchange factor (GEF) for Rac, whereas monomeric Cool-2 is a GEF for Cdc42 as well as Rac. However, unlike many GEFs, Cool-2 binds to activated forms of Cdc42 and Rac. Thus, we have investigated the functional consequences of these interactions. RESULTS: We show that the binding of activated Cdc42 to the Cool-2 dimer markedly enhances its ability to associate with GDP bound Rac1, resulting in a significant activation of Rac-GEF activity. While the Rac-specific GEF activity of Cool-2 is mediated through the Dbl homology (DH) domain from one monomer and the Pleckstrin homology domain from the other, activated Cdc42 interacts with the DH domain, most likely opposite the DH domain binding site for GDP bound Rac. Activated Rac also binds to Cool-2; however, it strongly inhibits the GEF activity of dimeric Cool-2. CONCLUSIONS: We provide evidence for novel mechanisms of allosteric regulation of the Rac-GEF activity of the Cool-2 dimer, involving stimulatory effects by Cdc42 and feedback inhibition by Rac. These findings demonstrate that by serving as a target for GTP bound Cdc42 and a GEF for Rac, Cool-2 mediates a GTPase cascade where the activation of Cdc42 is translated into the activation of Rac.

The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Publishing Authors By Initials

D Baird,Q Feng,RA Cerione,

For similar enzymes and coenzymes: enzymes: hydrolases: acid anhydride hydrolases: gtp phosphohydrolases: gtp-binding proteins: monomeric gtp-binding proteins: rho gtp-binding proteins: rac gtp-binding proteins research abstracts see: enzymes and coenzymes: enzymes: hydrolases: acid anhydride hydrolases: gtp phosphohydrolases: gtp-binding proteins: monomeric gtp-binding proteins: rho gtp-binding proteins: rac gtp-binding proteins research

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The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Journal Published:

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: Current biology : CB

VOLUME: 15

Page Numbers: 1-10

Journal Abbreviation: Curr. Biol.

ISSN: 0960-9822

DAY: 11

MONTH: Jan

YEAR: 2005

The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 9107782

The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Keywords Mesh Terms:

KEYWORDS: rac GTP-Binding Proteins

MESH TERMS: metabolism

Chemical & Substance for Abstract: The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade. Information

Substance Name: rac GTP-Binding Proteins

Registry Number: EC 3.6.5.2

Grant and Affiliation Information for The Cool-2/alpha-Pix protein mediates a Cdc42-Rac signaling cascade.

AFFILIATION: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.

Country: England

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MEDLINETA: Curr Biol

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