What is the state of G-proteins when there is no signal?

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Multiple Choice

What is the state of G-proteins when there is no signal?

G proteins act as molecular switches that are off when bound to GDP. In the absence of a signal, the receptor isn’t promoting GDP release, so the G alpha subunit stays bound to GDP and the heterotrimer (alpha with beta-gamma) sits in the inactive state at the inner membrane. Activation requires a signal to cause GDP to be exchanged for GTP, which turns the alpha subunit active and releases it from the beta-gamma dimer to propagate the signal. The switch is reset when the intrinsic or GAP-assisted hydrolysis of GTP converts it back to GDP, returning the protein to the inactive state. ATP binding or being free of any nucleotide isn’t part of the resting, inactive configuration.

G proteins act as molecular switches that are off when bound to GDP. In the absence of a signal, the receptor isn’t promoting GDP release, so the G alpha subunit stays bound to GDP and the heterotrimer (alpha with beta-gamma) sits in the inactive state at the inner membrane. Activation requires a signal to cause GDP to be exchanged for GTP, which turns the alpha subunit active and releases it from the beta-gamma dimer to propagate the signal. The switch is reset when the intrinsic or GAP-assisted hydrolysis of GTP converts it back to GDP, returning the protein to the inactive state. ATP binding or being free of any nucleotide isn’t part of the resting, inactive configuration.

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