21 Questions
Which statement about receptor enzymes is correct?
They contain an enzyme activity that acts on a cytosolic substrate
Which enzyme activity do receptor enzymes possess?
GTPase activity that acts on the cytosolic side
What is the main function of cholera toxins?
Inhibit the GTPase activity of Gi
Which process does dimerization of receptors upon ligand binding lead to?
Activation of G protein-coupled receptors
What is the role of adaptor proteins in signal transduction?
Facilitate interactions between signaling molecules
What is the primary function of stimulatory G protein (Gs) in signal transduction?
Activating adenylate cyclase to increase cAMP levels
What is the role of inhibitory G protein (Gi) in the G protein signaling pathway?
Inhibiting cAMP production by adenylate cyclase
What is a key function of the GTPase activity of G proteins?
To hydrolyze GTP to GDP and inactivate the G protein
How does desensitization of the β-adrenergic receptor contribute to cellular signaling?
By decreasing receptor responsiveness to ligands
Which of the following proteins play a crucial role in bridging activated receptors to downstream signaling pathways in cell signaling?
Adaptor proteins
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
What is the role of cyclic nucleotide phosphodiesterase in the cAMP signaling pathway?
It hydrolyzes cAMP to 5′ AMP
How does somatostatin affect the activity of adenylyl cyclase?
It inhibits adenylyl cyclase
What is the function of GTPase activator proteins (GAPs) in the regulation of G protein activity?
They increase the GTPase activity of G proteins
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
What is the function of adaptor proteins in cell signaling?
They hold together other protein molecules that function in concert
What is the effect of activating mutations in Gα on the concentration of cAMP in the cell?
They increase the concentration of cAMP
What is the effect of cholera toxin on the activity of Gsα?
It activates Gsα
What is the effect of GTP hydrolysis on the conformation of Ras?
It causes Ras to adopt its inactive conformation
What is the effect of defects in the G protein Ras on cell division?
They promote cell division
What is the effect of Gq-coupled receptors on the activity of phospholipase C?
They activate the activity of phospholipase C
Test your knowledge about the role of cyclic AMP as a second messenger for regulatory molecules and the functions of stimulatory G protein (Gs) and inhibitory G protein (Gi). Explore how G proteins are activated and the weak GTPase activity associated with them.
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