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  • Title: Dexras1 inhibits adenylyl cyclase.
    Author: Graham TE, Qiao Z, Dorin RI.
    Journal: Biochem Biophys Res Commun; 2004 Apr 02; 316(2):307-12. PubMed ID: 15020218.
    Abstract:
    Dexras1 is a steroid hormone-induced Ras family G protein that acts as a receptor-independent activator of signaling by Gi/o family heterotrimeric G proteins. We examined the effects of Dexras1 on the activity of adenylyl cylase, a target of inhibitory regulation by Gialpha x GTP. Constitutively active Gsalpha (Q227L) increased cAMP levels 43-fold above baseline, and Dexras1 expression inhibited cAMP levels by 61% (P < 0.01). Dexras1 mediated inhibition of adenylyl cyclase was blocked by treatment pertussis toxin or by co-expression of RGS4, but was not inhibited by with dominant-interfering (G203T or G204A) mutants of Gi alpha2. Dexras1 decreased forskolin-stimulated CREB activation (P < 0.01) and this activity was also inhibited by co-expression of RGS4. These findings indicate that Dexras1 expression leads to ligand-independent activation of both Gialpha- and G(beta)gamma-dependent arms of the Gi signaling cascade, and suggest that Dexras1 may exert physiologically relevant inhibitory effects on the cAMP-PKA-CREB.
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