Which of the following statements best describes an important feature of G protein activation?Group of answer choicesHydrolysis of GTP to GDP by the alpha subunit provides required energy for the activation of downstream signaling molecules.G proteins that interact with GPCRs are often referred to as monomeric.When ligand bound GPCRs interact with G proteins, they act as GEFs (guanine nucleotide exchange factors) leading to G protein activation.G proteins are equally activated by ATP or GTP.Neither G proteins nor GPCRs have lipid anchors, only downstream effector proteins do.
Question
Which of the following statements best describes an important feature of G protein activation?Group of answer choicesHydrolysis of GTP to GDP by the alpha subunit provides required energy for the activation of downstream signaling molecules.G proteins that interact with GPCRs are often referred to as monomeric.When ligand bound GPCRs interact with G proteins, they act as GEFs (guanine nucleotide exchange factors) leading to G protein activation.G proteins are equally activated by ATP or GTP.Neither G proteins nor GPCRs have lipid anchors, only downstream effector proteins do.
Solution
The statement that best describes an important feature of G protein activation is: "When ligand bound GPCRs interact with G proteins, they act as GEFs (guanine nucleotide exchange factors) leading to G protein activation."
Here's why:
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G proteins are heterotrimeric, not monomeric. They are composed of three different subunits: alpha, beta, and gamma.
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The hydrolysis of GTP to GDP by the alpha subunit does not provide the energy for the activation of downstream signaling molecules. Instead, it is the binding of GTP (not its hydrolysis) to the alpha subunit that activates the G protein.
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G proteins are not equally activated by ATP or GTP. They are specifically activated by GTP.
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Both G proteins and GPCRs can have lipid anchors. These anchors help to localize these proteins to the cell membrane where they can interact with each other.
Therefore, the statement "When ligand bound GPCRs interact with G proteins, they act as GEFs (guanine nucleotide exchange factors) leading to G protein activation" is the most accurate. This is because GEFs facilitate the exchange of GDP for GTP on the alpha subunit of the G protein, which leads to the activation of the G protein.
Similar Questions
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