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Questions and Answers
Which molecule is responsible for bringing PDK1 and Akt together at the membrane?
Which molecule is responsible for bringing PDK1 and Akt together at the membrane?
What is the key mediator that relaxes smooth muscle in blood vessels and visceral organs?
What is the key mediator that relaxes smooth muscle in blood vessels and visceral organs?
What is the enzyme responsible for producing NO from L-arginine?
What is the enzyme responsible for producing NO from L-arginine?
What molecule is produced from GTP by guanylyl cyclase (GC)?
What molecule is produced from GTP by guanylyl cyclase (GC)?
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What molecule activates a protein kinase (usually PKG) when elevated?
What molecule activates a protein kinase (usually PKG) when elevated?
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In smooth muscle, what does the disengagement of myosin from actin lead to?
In smooth muscle, what does the disengagement of myosin from actin lead to?
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Which G-protein mechanism is unique in that it uses Ca+2 and IP3 and DAG as second messenger systems?
Which G-protein mechanism is unique in that it uses Ca+2 and IP3 and DAG as second messenger systems?
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What effect does IP3 have when it is released into the cytosol?
What effect does IP3 have when it is released into the cytosol?
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What is the impact of Ca+2 binding to calmodulin?
What is the impact of Ca+2 binding to calmodulin?
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Which G-protein mechanism activates phospholipase C?
Which G-protein mechanism activates phospholipase C?
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What is the impact of Gi-α on adenylyl cyclase activity?
What is the impact of Gi-α on adenylyl cyclase activity?
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What is the impact of Gi-βγ on the membrane potential?
What is the impact of Gi-βγ on the membrane potential?
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Which of the following is NOT a function of cell membrane receptors in intracellular signaling?
Which of the following is NOT a function of cell membrane receptors in intracellular signaling?
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Which of the following best describes transduction in intracellular signaling?
Which of the following best describes transduction in intracellular signaling?
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What happens when the concentration of the first messenger (ligand) increases?
What happens when the concentration of the first messenger (ligand) increases?
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What is the role of the activated cell membrane receptor?
What is the role of the activated cell membrane receptor?
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What happens when the second messenger binds to and activates another protein?
What happens when the second messenger binds to and activates another protein?
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What happens to the second messenger over time?
What happens to the second messenger over time?
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Which of the following is true about G-protein-coupled receptors (GPCRs)?
Which of the following is true about G-protein-coupled receptors (GPCRs)?
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What happens when a ligand binds to a receptor associated with a Gs GPCR?
What happens when a ligand binds to a receptor associated with a Gs GPCR?
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What is the role of adenylyl cyclase in G-protein-coupled receptor signaling?
What is the role of adenylyl cyclase in G-protein-coupled receptor signaling?
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What is the role of protein kinase A (PKA) in G-protein-coupled receptor signaling?
What is the role of protein kinase A (PKA) in G-protein-coupled receptor signaling?
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What is the enzyme responsible for converting cAMP to 5'-AMP in G-protein-coupled receptor signaling?
What is the enzyme responsible for converting cAMP to 5'-AMP in G-protein-coupled receptor signaling?
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What happens when GTP is hydrolyzed to GDP in G-protein-coupled receptor signaling?
What happens when GTP is hydrolyzed to GDP in G-protein-coupled receptor signaling?
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According to the text, what happens to the cytosolic calcium concentration when a channel that allows calcium to cross the cell membrane is opened?
According to the text, what happens to the cytosolic calcium concentration when a channel that allows calcium to cross the cell membrane is opened?
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What is the membrane potential change called when a channel allows sodium to enter the cell?
What is the membrane potential change called when a channel allows sodium to enter the cell?
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Which ligand is an example of a receptor tyrosine kinase?
Which ligand is an example of a receptor tyrosine kinase?
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What is the key pathway associated with receptor tyrosine kinase activation?
What is the key pathway associated with receptor tyrosine kinase activation?
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What is the second messenger in the PI-3-Kinase-Akt pathway?
What is the second messenger in the PI-3-Kinase-Akt pathway?
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Activation of a G-protein-coupled receptor leads to the activation of a protein that binds to a __________ nucleotide
Activation of a G-protein-coupled receptor leads to the activation of a protein that binds to a __________ nucleotide
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The G-protein-coupled receptor (GPCR) family is the _______ family of cell membrane receptors
The G-protein-coupled receptor (GPCR) family is the _______ family of cell membrane receptors
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The activated G-protein modifies the activity of an ________
The activated G-protein modifies the activity of an ________
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The G-protein consists of three subunits: _______, ______, and ______
The G-protein consists of three subunits: _______, ______, and ______
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In the Gs GPCR pathway, Gs binds to and activates ____________
In the Gs GPCR pathway, Gs binds to and activates ____________
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The enzyme responsible for converting cAMP to 5'-AMP is _________
The enzyme responsible for converting cAMP to 5'-AMP is _________
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PIP3 is responsible for activating ______
PIP3 is responsible for activating ______
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PDK1 is responsible for activating ______
PDK1 is responsible for activating ______
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The production of cGMP is catalyzed by ______
The production of cGMP is catalyzed by ______
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Elevations in cytosolic cGMP activates a protein kinase called ______
Elevations in cytosolic cGMP activates a protein kinase called ______
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Elevations in cytosolic calcium can activate ______
Elevations in cytosolic calcium can activate ______
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NO binds to and activates ______
NO binds to and activates ______
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Gi-α inactivates ______
Gi-α inactivates ______
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Opening of K+ channels brings the cell closer to its ______ potential for K+
Opening of K+ channels brings the cell closer to its ______ potential for K+
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The cell membrane is inside-negative with a low cytosolic concentration of sodium and a high concentration of K+
The cell membrane is inside-negative with a low cytosolic concentration of sodium and a high concentration of K+
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IP3 is a 2nd messenger that causes release of ______ from where it’s stored in the endoplasmic reticulum (ER)
IP3 is a 2nd messenger that causes release of ______ from where it’s stored in the endoplasmic reticulum (ER)
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Ca+2 can bind to and activate a number of ______
Ca+2 can bind to and activate a number of ______
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Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
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Depolarization is the term used when the membrane becomes more ______
Depolarization is the term used when the membrane becomes more ______
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Hyperpolarization is the term used when the membrane becomes more ______
Hyperpolarization is the term used when the membrane becomes more ______
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The activation of certain membrane-associated proteins is impacted by making the membrane more ______ or more ______
The activation of certain membrane-associated proteins is impacted by making the membrane more ______ or more ______
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Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
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Hyperpolarization is the term used when the membrane becomes more ______
Hyperpolarization is the term used when the membrane becomes more ______
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What is the membrane potential change called when a channel allows sodium to enter the cell?
What is the membrane potential change called when a channel allows sodium to enter the cell?
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The activation of certain membrane-associated proteins is impacted by making the membrane more ______ or more ______
The activation of certain membrane-associated proteins is impacted by making the membrane more ______ or more ______
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Elevations in cytosolic calcium can activate ______
Elevations in cytosolic calcium can activate ______
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Receptors in the cell membrane are key in detecting ______ signals and modifying cell function based on those signals
Receptors in the cell membrane are key in detecting ______ signals and modifying cell function based on those signals
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Transduction is the intracellular events that transform the ______ signal into an intracellular signal
Transduction is the intracellular events that transform the ______ signal into an intracellular signal
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Additional signaling events involving the membrane: source of some ______ messengers
Additional signaling events involving the membrane: source of some ______ messengers
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Additional signaling events involving the membrane: site where some 2nd messengers ______
Additional signaling events involving the membrane: site where some 2nd messengers ______
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Additional signaling events involving the membrane: site where ionic 2nd messengers are ______
Additional signaling events involving the membrane: site where ionic 2nd messengers are ______
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Additional signaling events involving the membrane: important site where regulatory proteins and enzymes ______ and integrate signaling
Additional signaling events involving the membrane: important site where regulatory proteins and enzymes ______ and integrate signaling
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Receptors in the cell membrane are key in detecting ______ signals and modifying cell function based on those signals
Receptors in the cell membrane are key in detecting ______ signals and modifying cell function based on those signals
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That protein activated a mechanism (in this case an enzyme) that increased the intracellular concentration of the active form of a second ______
That protein activated a mechanism (in this case an enzyme) that increased the intracellular concentration of the active form of a second ______
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The second messenger binds to and activates another ______… and that protein will activate or inactivate other biochemical signaling cascades that have some sort of effect
The second messenger binds to and activates another ______… and that protein will activate or inactivate other biochemical signaling cascades that have some sort of effect
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Inactive system: extracellular signal ______
Inactive system: extracellular signal ______
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As time goes on: ligand releases from receptor receptor-associated effectors ______ 2nd messenger is either metabolized or removed 2nd messenger “inactivator”
As time goes on: ligand releases from receptor receptor-associated effectors ______ 2nd messenger is either metabolized or removed 2nd messenger “inactivator”
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Activation of a G-protein-coupled receptor leads to the activation of a protein that binds to a ______ nucleotide
Activation of a G-protein-coupled receptor leads to the activation of a protein that binds to a ______ nucleotide
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The G-protein consists of three subunits: ______, ______, and ______
The G-protein consists of three subunits: ______, ______, and ______
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Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
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Receptors in the cell membrane are key in detecting ______ signals and modifying cell function based on those signals
Receptors in the cell membrane are key in detecting ______ signals and modifying cell function based on those signals
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What is the impact of Gi-α on adenylyl cyclase activity?
What is the impact of Gi-α on adenylyl cyclase activity?
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What is the membrane potential change called when a channel allows sodium to enter the cell?
What is the membrane potential change called when a channel allows sodium to enter the cell?
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Gs releases GDP and binds GTP at the alpha subunit ▪ The βγ subunit detaches from the G-protein 3. Gs binds to and activates adenylyl cyclase ▪ Membrane-bound enzyme that converts ATP to ______
Gs releases GDP and binds GTP at the alpha subunit ▪ The βγ subunit detaches from the G-protein 3. Gs binds to and activates adenylyl cyclase ▪ Membrane-bound enzyme that converts ATP to ______
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PK A phosphorylates a multitude of ______ proteins
PK A phosphorylates a multitude of ______ proteins
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Inactivation of cAMP results when it is converted to 5’-AMP ▪ Enzyme – cyclic AMP ______
Inactivation of cAMP results when it is converted to 5’-AMP ▪ Enzyme – cyclic AMP ______
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A ligand binds to a receptor associated with a ______ Gprotein
A ligand binds to a receptor associated with a ______ Gprotein
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Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
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NO is a _______ messenger – one of the only ones that can diffuse across the cell membrane and impact other cells
NO is a _______ messenger – one of the only ones that can diffuse across the cell membrane and impact other cells
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______ is responsible for activating guanylyl cyclase (GC)
______ is responsible for activating guanylyl cyclase (GC)
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Elevations in cytosolic ______ activates a protein kinase (usually PKG)
Elevations in cytosolic ______ activates a protein kinase (usually PKG)
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In smooth muscle, the disengagement of myosin from actin leads to _______ muscle relaxation
In smooth muscle, the disengagement of myosin from actin leads to _______ muscle relaxation
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______ brings PDK1 and Akt together at the membrane
______ brings PDK1 and Akt together at the membrane
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NO is produced enzymatically by the action of nitric oxide synthase (NOs) on _______
NO is produced enzymatically by the action of nitric oxide synthase (NOs) on _______
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Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
Opening a channel that allows calcium to cross the cell membrane would increase the cytosolic ______ concentration
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Depolarization is the term used when the membrane becomes more ______
Depolarization is the term used when the membrane becomes more ______
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Hyperpolarization is the term used when the membrane becomes more ______
Hyperpolarization is the term used when the membrane becomes more ______
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The activation of certain membrane-associated proteins is impacted by making the membrane more ______ or more ______
The activation of certain membrane-associated proteins is impacted by making the membrane more ______ or more ______
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The Ras-Raf-MAP kinase pathway is the pathway most commonly associated with ______ activation
The Ras-Raf-MAP kinase pathway is the pathway most commonly associated with ______ activation
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Study Notes
Protein Interactions and Mediators
- PDK1 and Akt are brought together at the membrane by the molecule PIP3.
- The key mediator that relaxes smooth muscle in blood vessels and visceral organs is Nitric Oxide (NO).
- Nitric oxide synthase (NOS) is the enzyme that produces NO from L-arginine.
- Guanylyl cyclase (GC) produces cGMP from GTP.
- cGMP activates a protein kinase, usually PKG, when elevated.
Smooth Muscle Dynamics
- Disengagement of myosin from actin in smooth muscle leads to muscle relaxation.
- The G-protein mechanism that involves Ca²⁺ relies on IP3 and DAG as second messengers.
- IP3 triggers the release of Ca²⁺ from the endoplasmic reticulum (ER) when released into the cytosol.
- Ca²⁺ binding to calmodulin activates various target proteins.
G-Protein Coupling and Effects
- The G-protein mechanism activating phospholipase C is associated with certain types of GPCRs.
- Gi-α inhibits adenylyl cyclase activity, leading to reduced cAMP production.
- Gi-βγ can hyperpolarize the membrane by affecting the membrane potential.
Cell Membrane Receptors and Signaling
- Functions of cell membrane receptors in intracellular signaling include detecting signals but do not typically encompass channel characteristics.
- Transduction refers to the process that converts an extracellular signal into an intracellular signal.
- An increase in the first messenger's concentration amplifies intracellular responses.
- Activated cell membrane receptors initiate downstream signaling cascades.
- Second messengers amplify the signaling effect when they bind to target proteins.
G-Protein-Coupled Receptors (GPCRs)
- GPCR family is the largest family of cell membrane receptors.
- When a ligand binds to a Gs GPCR, it activates adenylyl cyclase.
- Adenylyl cyclase converts ATP to cAMP, leading to various signaling effects.
- PKA (protein kinase A) phosphorylates target proteins, affecting multiple cellular processes.
Second Messengers and Pathways
- Phosphodiesterase is responsible for converting cAMP to 5'-AMP, leading to its inactivation.
- GTP hydrolysis to GDP leads to the inactivation of the G-protein in GPCR signaling.
- The change in cytosolic calcium concentration occurs when channels open, facilitating calcium entry.
- Depolarization occurs when sodium enters the cell, while hyperpolarization occurs when the cell becomes more negative.
Key Signaling Components
- Receptor tyrosine kinases are crucial for signaling pathways like the Ras-Raf-MAP kinase pathway.
- PIP3 activates PDK1, which subsequently activates Akt.
- The production of cGMP is catalyzed by activation of guanylyl cyclase, often by NO.
- Activated PKA regulates various other signaling proteins, further propagating the signal.
Membrane Potential and Associated Effects
- Opening K⁺ channels can bring the cell closer to its equilibrium potential.
- Receptors enable the detection of extracellular signals and their integration into cellular functions.
- Membrane-associated proteins are influenced by changes in membrane potential, affecting their activity.
Signal Termination and Regulation
- With time, ligands detach from receptors, leading to a decrease in signaling as second messengers are metabolized or removed.
- Active G-protein components include three subunits: α, β, and γ.
- Ca²⁺ as a second messenger can activate additional signaling pathways, emphasizing its role in various cellular processes.
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Description
Quiz: Understanding G-Protein Mechanisms - Gi and Gq Test your knowledge on the different G-protein mechanisms with this quiz. Discover the roles of Gi and Gq in modulating cellular responses and learn how they activate second messengers to regulate effector functions in various cell types. Challenge yourself and deepen your understanding of these important signaling pathways.
