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    G Protein Isolated Mutations

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    Siganl tansducing tirmeric G proteins consist of three subunits designated as alpha, beta, gamma. Suppose you have isolated a mutant G alpha subunit that has an increased GTPase activity. What effect would this mutation have on the G protein and the effector protein? Why?

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    g protein

    Siganl tansducing tirmeric G proteins consist of three subunits designated as alpha, beta, gamma. Suppose you have isolated a mutant G alpha subunit that has an increased GTPase activity. What effect would this mutation have on the G protein and the effector protein? Why?

    Answer:
    The heterotrimeric G protein G(s) couples hormone receptors (as well as other receptors) to the effector enzyme adenylyl cyclase and is therefore required for hormone-stimulated intracellular cAMP generation. Receptors activate G(s) by promoting exchange of GTP for GDP on the G(s) alpha-subunit (G(s)alpha) while an intrinsic GTPase activity of G(s)alpha that hydrolyzes bound GTP to GDP leads to deactivation.
    Substitution of Arg258, a residue within the GTPase domain of the heterotrimeric guanine nucleotide binding protein (G protein) -subunit ( s), to alanine ( s-R258A) results in decreased activation by receptor or aluminum fluoride (AlF4 ) and increased basal GDP ...

    Solution Summary

    The expert examines G Protein isolation mutations. The three subunits designated as alphas for trimeric G proteins are determined.

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