Cell Communication 2

What is the common feature shared by all G proteins?

They can self-inactivate

Which type of G protein is involved in the cAMP signal pathway as a stimulatory component?

Gs

How many types of G protein-coupled receptors (GPCRs) have been identified in humans?

900

Which receptor is often used as a model for signal transduction among GPCRs?

Beta-adrenergic receptor Signup and view all the answers

What did the scientists receive the Nobel Prize in Physiology and Medicine for in 1994?

Role of G proteins in cell signaling Signup and view all the answers

Which type of receptor includes metabotropic receptors that bind to G proteins?

GPCRs Signup and view all the answers

What is the role of cAMP in the signal transduction pathway described?

Allosterically activates PKA Signup and view all the answers

Which hormone increases glycogenolysis and suppresses glycogenesis?

Epinephrine Signup and view all the answers

What is the primary function of Phosphokinase A (PKA) in the cascade?

Phosphorylates cellular proteins Signup and view all the answers

Which process leads to the termination of the GPCR pathway?

Desensitization Signup and view all the answers

What happens when Gs exchanges GDP for GTP?

Gs is activated Signup and view all the answers

Which of the following hormones inhibits Adenylyl Cyclase, lowering cAMP levels?

Somatostatin Signup and view all the answers

What is the role of a GPCR?

Generating an intracellular second messenger Signup and view all the answers

How does the G protein α-subunit become activated?

Exchanges bound GDP for GTP Signup and view all the answers

What causes the dissociation of the β/γ complex from the G protein α-subunit?

Activation by the ligand/GPCR complex Signup and view all the answers

What increases the intrinsic GTPase activity of G proteins?

GTPase Activator Proteins (GAPs) Signup and view all the answers

What enzyme ultimately reduces [cAMP] levels?

Phosphodiesterase (PDE) Signup and view all the answers

Which protein hydrolyzes GTP to GDP and becomes inactive after a certain time?

G protein α-subunit Signup and view all the answers

What is the role of GAPs in the signal termination pathway?

Speed up the intrinsic GTPase activity of G protein Signup and view all the answers

How does β-adrenergic receptor kinase (βARK) contribute to desensitization?

Draws to the receptor and phosphorylates it Signup and view all the answers

What happens during receptor sequestration?

Removal of receptors from the membrane through endocytosis Signup and view all the answers

How does β-arrestin contribute to resensitization in the signal termination pathway?

Dissociates from receptors in endocytic vesicles Signup and view all the answers

What leads to the deactivation of the pathway in response to low concentrations of epinephrine?

Dissociation of epinephrine from its receptor Signup and view all the answers

Which protein initiates receptor sequestration and removal from the membrane?

β-adrenergic receptor kinase (βARK) Signup and view all the answers

What is the main function of GPCRs in cell signaling?

Mediate responses to signals from other cells Signup and view all the answers

Which type of G protein is associated with the cAMP signal pathway as an inhibitory component?

Gi Signup and view all the answers

How many types of GPCR have been identified in humans for detecting hormones and endogenous ligands?

350 Signup and view all the answers

What is the role of G proteins in cellular signaling?

Act as molecular binary switches with built-in timers Signup and view all the answers

Which receptor type is a prototype for all GPCRs and is commonly targeted by beta blockers?

β-adrenergic receptor Signup and view all the answers

What did the scientists receive the Nobel Prize in Physiology and Medicine for in 1994 related to G proteins?

Role of G proteins in signal transduction in cells Signup and view all the answers

What is the role of the G protein α subunit (Gα) prior to activation?

It has GDP bound and is inactive Signup and view all the answers

Which enzyme is responsible for ultimately reducing the levels of [cAMP]?

Phosphodiesterase Signup and view all the answers

What activity determines how long the G protein remains 'on'?

GTPase Activator Proteins (GAPs) Signup and view all the answers

Which molecule is exchanged for GTP in the G protein α subunit upon activation?

GDP Signup and view all the answers

What is the function of Adenylate Cyclase in the signal transduction pathway?

Activates Protein Kinase A Signup and view all the answers

How does the activation of Protein Kinase A (PKA) affect downstream targets?

Stimulates effector enzymes/enzymes Signup and view all the answers

Which enzyme catalyzes the formation of cAMP in the signal transduction pathway?

Adenylyl Cyclase Signup and view all the answers

What is the primary function of Protein Kinase A (PKA) in the signal cascade?

Phosphorylates cellular proteins resulting in a cellular response Signup and view all the answers

Which hormone suppresses glycogenesis and increases glycogenolysis?

Epinephrine Signup and view all the answers

What is the net effect of the signal cascade involving GPCR, Gs, cAMP, and PKA?

Amplification of the hormone signal Signup and view all the answers

Which mechanism causes the termination of the GPCR pathway after the stimulus has ended?

Desensitization Signup and view all the answers

What effect do hormones like somatostatin, adenosine, and PGE1 have on Adenylyl Cyclase activity?

Inhibition Signup and view all the answers

What is the role of GAPs (GTPase activator proteins) in the signal termination pathway?

Speed up signal termination by increasing G protein's GTP hydrolysis rate Signup and view all the answers

Which protein initiates receptor sequestration by phosphorylating the receptor and creating a binding site for β-arrestin?

β-adrenergic receptor kinase (βARK) Signup and view all the answers

What is the function of β-arrestin (β-arr) in the desensitization process of the signal termination pathway?

Promote re-sensitization by stopping the interaction between receptor and G protein Signup and view all the answers

During continued presence of epinephrine, what happens to receptors sequestered in endocytic vesicles?

They dephosphorylate, allowing them to return to the membrane Signup and view all the answers

Which process reduces the cellular response to a signal even when the signal continues?

Desensitization Signup and view all the answers

What is the role of intrinsic GTPase activity of G protein in the signal termination pathway?

Hydrolyze bound GTP to GDP, leading to pathway inactivation Signup and view all the answers

What is the main function of GPCRs in cell signaling?

Mediate most responses to signals from the external world and other cells Signup and view all the answers

Which hormone suppresses glycogenesis and increases glycogenolysis?

Epinephrine Signup and view all the answers

What type of receptors include metabotropic receptors that bind to G proteins?

GPCRs Signup and view all the answers

What did the scientists receive the Nobel Prize in Physiology and Medicine for in 1994 related to G proteins?

Discovery of G-proteins and their role in signal transduction in cells Signup and view all the answers

Which enzyme catalyzes the formation of cAMP in the signal transduction pathway?

Adenylate Cyclase Signup and view all the answers

What happens when Gs exchanges GDP for GTP?

It activates adenylyl cyclase Signup and view all the answers

What is the role of GTPase activator proteins (GAPs) in the signal termination pathway?

Catalyze the hydrolysis of GTP to GDP Signup and view all the answers

During continued presence of epinephrine, what initiates receptor sequestration?

Beta-adrenergic receptor kinase (βARK) Signup and view all the answers

What is the outcome of desensitization in the signal termination pathway?

Reduced cellular response Signup and view all the answers

How does β-arrestin contribute to resensitization in the signal termination pathway?

Dissociates from receptors in endocytic vesicles Signup and view all the answers

What enzyme is responsible for speeding up the intrinsic GTPase activity of G protein in the signal termination pathway?

Beta-adrenergic receptor kinase (βARK) Signup and view all the answers

What action does low concentrations of epinephrine cause in the signal termination pathway?

Deactivation of the pathway Signup and view all the answers

What happens to the G protein alpha subunit once it becomes activated?

It exchanges GDP for GTP Signup and view all the answers

Which protein stimulates the rapid inactivation of G proteins by strongly stimulating their GTPase activity?

GTPase Activator Protein (GAP) Signup and view all the answers

What is the function of Adenylate Cyclase in the cell signaling pathway?

Generating cAMP from ATP Signup and view all the answers

How are GTP-bound G protein alpha subunits and beta/gamma complexes involved in cell signaling?

They activate effector proteins/enzymes Signup and view all the answers

Which molecule ultimately reduces the levels of intracellular cAMP?

[cAMP] phosphodiesterase (PDE) Signup and view all the answers

What causes the dissociation of the beta/gamma complex from the G protein alpha subunit?

Activation by ligand/GPCR complex Signup and view all the answers

What is the main effect of the binding of a ligand to a receptor in the signal transduction pathway?

Activation of Adenylyl Cyclase (AC) Signup and view all the answers

What is the role of Gs -subunit in the signal transduction pathway?

Activating Adenylate Cyclase Signup and view all the answers

Which hormone suppresses glycogenolysis and stimulates glycogenesis?

Insulin Signup and view all the answers

What is the mechanism by which hormones like somatostatin suppress protein phosphorylation?

Inhibition of Adenylyl Cyclase Signup and view all the answers

What is the net effect of the signal cascade involving GPCR, Gs, cAMP, and PKA?

Amplification of the hormone signal Signup and view all the answers

How do signal transducing systems adapt to the continued presence of a signal after termination?

By becoming less sensitive through desensitization Signup and view all the answers

Cell Communication 2

Questions and Answers

What is the common feature shared by all G proteins?

Which type of G protein is involved in the cAMP signal pathway as a stimulatory component?

How many types of G protein-coupled receptors (GPCRs) have been identified in humans?

Which receptor is often used as a model for signal transduction among GPCRs?

What did the scientists receive the Nobel Prize in Physiology and Medicine for in 1994?

Which type of receptor includes metabotropic receptors that bind to G proteins?

What is the role of cAMP in the signal transduction pathway described?

Which hormone increases glycogenolysis and suppresses glycogenesis?

What is the primary function of Phosphokinase A (PKA) in the cascade?

Which process leads to the termination of the GPCR pathway?

What happens when Gs exchanges GDP for GTP?

Which of the following hormones inhibits Adenylyl Cyclase, lowering cAMP levels?

What is the role of a GPCR?

How does the G protein α-subunit become activated?

What causes the dissociation of the β/γ complex from the G protein α-subunit?

What increases the intrinsic GTPase activity of G proteins?

What enzyme ultimately reduces [cAMP] levels?

Which protein hydrolyzes GTP to GDP and becomes inactive after a certain time?

What is the role of GAPs in the signal termination pathway?

How does β-adrenergic receptor kinase (βARK) contribute to desensitization?

What happens during receptor sequestration?

How does β-arrestin contribute to resensitization in the signal termination pathway?

What leads to the deactivation of the pathway in response to low concentrations of epinephrine?

Which protein initiates receptor sequestration and removal from the membrane?

What is the main function of GPCRs in cell signaling?

Which type of G protein is associated with the cAMP signal pathway as an inhibitory component?

How many types of GPCR have been identified in humans for detecting hormones and endogenous ligands?

What is the role of G proteins in cellular signaling?

Which receptor type is a prototype for all GPCRs and is commonly targeted by beta blockers?

What did the scientists receive the Nobel Prize in Physiology and Medicine for in 1994 related to G proteins?

What is the role of the G protein α subunit (Gα) prior to activation?

Which enzyme is responsible for ultimately reducing the levels of [cAMP]?

What activity determines how long the G protein remains 'on'?

Which molecule is exchanged for GTP in the G protein α subunit upon activation?

What is the function of Adenylate Cyclase in the signal transduction pathway?

How does the activation of Protein Kinase A (PKA) affect downstream targets?

Which enzyme catalyzes the formation of cAMP in the signal transduction pathway?

What is the primary function of Protein Kinase A (PKA) in the signal cascade?

Which hormone suppresses glycogenesis and increases glycogenolysis?

What is the net effect of the signal cascade involving GPCR, Gs, cAMP, and PKA?

Which mechanism causes the termination of the GPCR pathway after the stimulus has ended?

What effect do hormones like somatostatin, adenosine, and PGE1 have on Adenylyl Cyclase activity?

What is the role of GAPs (GTPase activator proteins) in the signal termination pathway?

Which protein initiates receptor sequestration by phosphorylating the receptor and creating a binding site for β-arrestin?

What is the function of β-arrestin (β-arr) in the desensitization process of the signal termination pathway?

During continued presence of epinephrine, what happens to receptors sequestered in endocytic vesicles?

Which process reduces the cellular response to a signal even when the signal continues?

What is the role of intrinsic GTPase activity of G protein in the signal termination pathway?

What is the main function of GPCRs in cell signaling?

Which hormone suppresses glycogenesis and increases glycogenolysis?

What type of receptors include metabotropic receptors that bind to G proteins?

What did the scientists receive the Nobel Prize in Physiology and Medicine for in 1994 related to G proteins?

Which enzyme catalyzes the formation of cAMP in the signal transduction pathway?

What happens when Gs exchanges GDP for GTP?

What is the role of GTPase activator proteins (GAPs) in the signal termination pathway?

During continued presence of epinephrine, what initiates receptor sequestration?

What is the outcome of desensitization in the signal termination pathway?

How does β-arrestin contribute to resensitization in the signal termination pathway?

What enzyme is responsible for speeding up the intrinsic GTPase activity of G protein in the signal termination pathway?

What action does low concentrations of epinephrine cause in the signal termination pathway?

What happens to the G protein alpha subunit once it becomes activated?

Which protein stimulates the rapid inactivation of G proteins by strongly stimulating their GTPase activity?

What is the function of Adenylate Cyclase in the cell signaling pathway?

How are GTP-bound G protein alpha subunits and beta/gamma complexes involved in cell signaling?

Which molecule ultimately reduces the levels of intracellular cAMP?

What causes the dissociation of the beta/gamma complex from the G protein alpha subunit?

What is the main effect of the binding of a ligand to a receptor in the signal transduction pathway?

What is the role of Gs -subunit in the signal transduction pathway?

Which hormone suppresses glycogenolysis and stimulates glycogenesis?

What is the mechanism by which hormones like somatostatin suppress protein phosphorylation?

What is the net effect of the signal cascade involving GPCR, Gs, cAMP, and PKA?

How do signal transducing systems adapt to the continued presence of a signal after termination?

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