Cyclic AMP and G Proteins Quiz

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Which statement about receptor enzymes is correct?

They contain an enzyme activity that acts on a cytosolic substrate (correct)

They have a ligand-binding site on the cytosolic side of the membrane

They are not usually membrane-associated proteins

They contain an enzyme activity that acts on the extracellular ligand

Which enzyme activity do receptor enzymes possess?

GTPase activity that acts on the cytosolic side (correct)

Ligase activity that acts on the cell membrane

Kinase activity that acts on the extracellular ligand

Phosphatase activity that acts on the intracellular domain

What is the main function of cholera toxins?

Stimulate the phosphatase activity of FGFR

Activate the GTPase activity of Gs

Enhance the kinase activity of TrkA

Inhibit the GTPase activity of Gi (correct)

Which process does dimerization of receptors upon ligand binding lead to?

Activation of G protein-coupled receptors Signup and view all the answers

What is the role of adaptor proteins in signal transduction?

Facilitate interactions between signaling molecules Signup and view all the answers

What is the primary function of stimulatory G protein (Gs) in signal transduction?

Activating adenylate cyclase to increase cAMP levels Signup and view all the answers

What is the role of inhibitory G protein (Gi) in the G protein signaling pathway?

Inhibiting cAMP production by adenylate cyclase Signup and view all the answers

What is a key function of the GTPase activity of G proteins?

To hydrolyze GTP to GDP and inactivate the G protein Signup and view all the answers

How does desensitization of the β-adrenergic receptor contribute to cellular signaling?

By decreasing receptor responsiveness to ligands Signup and view all the answers

Which of the following proteins play a crucial role in bridging activated receptors to downstream signaling pathways in cell signaling?

Adaptor proteins Signup and view all the answers

What is the primary function of effector enzymes in the plasma membrane in the context of cellular signaling?

To generate second messengers such as cAMP and cGMP Signup and view all the answers

What is the role of cyclic nucleotide phosphodiesterase in the cAMP signaling pathway?

It hydrolyzes cAMP to 5′ AMP Signup and view all the answers

How does somatostatin affect the activity of adenylyl cyclase?

It inhibits adenylyl cyclase Signup and view all the answers

What is the function of GTPase activator proteins (GAPs) in the regulation of G protein activity?

They increase the GTPase activity of G proteins Signup and view all the answers

What is the role of β-arrestin in the desensitization of the β-adrenergic receptor?

It blocks the receptor sites that interact with the G protein Signup and view all the answers

What is the function of adaptor proteins in cell signaling?

They hold together other protein molecules that function in concert Signup and view all the answers

What is the effect of activating mutations in Gα on the concentration of cAMP in the cell?

They increase the concentration of cAMP Signup and view all the answers

What is the effect of cholera toxin on the activity of Gsα?

It activates Gsα Signup and view all the answers

What is the effect of GTP hydrolysis on the conformation of Ras?

It causes Ras to adopt its inactive conformation Signup and view all the answers

What is the effect of defects in the G protein Ras on cell division?

They promote cell division Signup and view all the answers

What is the effect of Gq-coupled receptors on the activity of phospholipase C?

They activate the activity of phospholipase C Signup and view all the answers