What question did this study set out to answer?

To determine whether the guanine nucleotide exchange factor Sos directly couples the activation of Ras and Rac GTPase signaling pathways.

January 23, 1998Science

Coupling of Ras and Rac Guanosine Triphosphatases Through the Ras Exchanger Sos

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To determine whether the guanine nucleotide exchange factor Sos directly couples the activation of Ras and Rac GTPase signaling pathways.
Assayed guanine nucleotide exchange activity of the isolated DH domain and tandem DH-PH domain of Sos on Rac and Cdc42 both in vitro and in transfected COS-1 cells.
Coexpressed tandem DH-PH-Sos with activated Ras in the presence or absence of signaling downstream effectors to assess dependence on MAPK and PI3K pathways.
The isolated DH domain of Sos stimulated guanine nucleotide exchange specifically on Rac, but not Cdc42, in vitro and in vivo.
Tandem DH-PH-Sos was inactive toward Rac alone but regained robust Rac-stimulating activity when coexpressed with activated Ras.
Ras-induced reactivation of DH-PH-Sos required activation of phosphoinositide 3-kinase, while remaining independent of mitogen-activated protein kinase.

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Implication

Experimental study demonstrates Sos-mediated activation of Rac by active Ras in COS-1 cells, indicating a direct molecular coupling mechanism between Ras and Rac signaling pathways.

Cite This Study

Nimnual et al. (1998) studied this question.

synapsesocial.com/papers/6a0cc78e9d761985b14a48b1 https://doi.org/10.1126/science.279.5350.560

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Implication

Experimental study demonstrates Sos-mediated activation of Rac by active Ras in COS-1 cells, indicating a direct molecular coupling mechanism between Ras and Rac signaling pathways.

Coupling of Ras and Rac Guanosine Triphosphatases Through the Ras Exchanger Sos

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Discussion

Implication

Cite This Study

Coupling of Ras and Rac Guanosine Triphosphatases Through the Ras Exchanger Sos

Key Points

Discussion

Implication

Cite This Study

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