84 Questions
Gs-GTP stimulates the activation of Adenylyl Cyclase (AC).
True
The increased cAMP level leads to the inhibition of protein kinase A (PKA).
False
Gi/o-GTP inhibits the activity of Adenylyl Cyclase (AC) and lowers cellular cAMP level.
True
CAMP can also modulate the activity of several Protein Kinase C (PKC).
False
IP3 acts on the endoplasmic reticulum (ER) and triggers the release of Na+ into the cytoplasm.
False
Phospholipase C- (PLC) catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG).
True
The cAMP Signalling Pathway involves Gq/11-GTP and activation of Adenylyl Cyclase (AC).
False
The increased cAMP level leads to decreased PKA activation.
False
Gi/o-GTP activates the activity of Adenylyl Cyclase (AC) and increases cellular cAMP level.
False
Ca2+ modulates the activity of Ca2+-dependent effector proteins.
True
Phosphatidylinositol-biphosphate (PIP2) is cleaved by Gα-GTP activated phospholipase C-β (PLC-β) to generate 2nd messengers IP3 and DAG?
True
IP3 diffuses through the cytosol and releases Ca2+ from the ER, while DAG activates protein kinase C?
True
The free Gβγ dimer plays key roles in GPCR signaling by regulating a host of downstream effectors such as voltage-gated Na+ channels?
False
Desensitization & internalization of GPCRs is controlled by the sequential action of G protein-coupled receptor kinases (GRKs) and cytoplasmic adaptor proteins?
True
β-arrestins bind to phosphorylated GPCR & facilitate receptor internalization?
True
Internalized GPCRs are trafficked to lysosomes for recycling back to the cell surface for future signaling?
False
Norepinephrine and epinephrine act on α1 receptors?
True
Acetylcholine acts on M2 receptors for autonomic nervous system control of heart function?
False
Histamine H1 receptor mediates the actions of histamine?
True
Dopamine D1 and D5 receptors are part of the GPCR receptor superfamily?
True
Serotonin (5-HT) acts on 5-HT4, 5-HT6, and 5-HT7 receptors?
True
GPCRs play a role in mediating autonomic nervous system control of heart function?
True
What is the role of DAG in the IP3/Ca2+ signalling pathway?
It activates protein kinase C
Which enzyme catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG)?
Phospholipase C- (PLC)
What is the function of β-arrestins in GPCR desensitization and intracellular trafficking?
They bind to phosphorylated GPCR & facilitate receptor internalization
Which type of receptor mediates the actions of serotonin (5-HT)?
5-HT4, 5-HT6, and 5-HT7 receptors
What happens when Gi/o-GTP is activated?
It inhibits the activity of Adenylyl Cyclase (AC)
What is the main role of the free Gβγ dimer in GPCR signaling?
It regulates a host of downstream effectors such as voltage-gated Na+ channels
What is the effect of increased cAMP level on protein kinase A (PKA) activation?
It leads to increased PKA activation
What is the role of GRKs in GPCR desensitization?
$4 * 2$
What are the downstream effectors regulated by the free Gβγ dimer in GPCR signaling?
Voltage-gated Ca++ channels, inwardly-rectifying K channels, GPCR kinases, phosphoinositide 3 kinases, adenylyl cyclase, phospholipase C-
What are the 2nd messengers generated by Gα-GTP activated phospholipase C-?
IP3 and Diacylglycerol (DAG)
What is the role of Gαs-GTP in the cAMP signaling pathway?
Stimulates the activation of Adenylyl Cyclase (AC)
What is the effect of Gαi/o-GTP on the cAMP signaling pathway?
Inhibits the activity of Adenylyl Cyclase (AC)
What is the function of IP3 in the IP3/Ca signaling pathway?
Triggers the release of Ca2+ into the cytoplasm
What is the main role of Phospholipase C-β (PLC-β) in the IP3/Ca signaling pathway?
Triggers the release of Ca2+ into the cytoplasm
What is the cellular response to increased cAMP levels?
Activation of protein kinase A (PKA) and phosphorylation of downstream effector targets
What cellular response is mediated by Gαi/o-GTP in the cAMP signaling pathway?
Inhibition of protein kinase A (PKA) and reduced cellular response
What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?
Phosphorylation of downstream effector targets by protein kinase A (PKA)
What is the primary role of Gq/11-GTP in the IP3/Ca signaling pathway?
Triggers the release of Ca2+ into the cytoplasm
What is the effect of Gs-GTP on the activity of Adenylyl Cyclase (AC)?
Stimulates the activation of Adenylyl Cyclase (AC)
What is modulated by cAMP in addition to PKA activation?
Guanine Exchange Factors (GEFs) and ion channels
What is the role of Gαs-GTP in the cAMP signaling pathway?
Stimulates the activation of Adenylyl Cyclase (AC)
What is modulated by cAMP in addition to PKA activation?
Protein Kinase C (PKC) activity
What is the primary role of Gq/11-GTP in the IP3/Ca signaling pathway?
Activates Phospholipase C- (PLC)
What happens when Gi/o-GTP is activated?
Inhibits the activity of Adenylyl Cyclase (AC) and lowers cellular cAMP level
What is the effect of increased cAMP level on protein kinase A (PKA) activation?
Increases PKA activation
What is modulated by cAMP in addition to PKA activation?
Ca2+-dependent effector proteins activity
What is the role of GRKs in GPCR desensitization?
Facilitate receptor internalization and desensitization
What is the function of IP3 in the IP3/Ca signaling pathway?
Triggers the release of Ca2+ into the cytoplasm
What is the role of DAG in the IP3/Ca2+ signalling pathway?
Modulates the activity of Ca2+-dependent effector proteins
What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?
Activation of multiple downstream effector targets
What is the primary function of phosphatidylinositol-biphosphate (PIP2) in the IP3/Ca signaling pathway?
Generates diacylglycerol (DAG)
What is the role of Gαs-GTP in the cAMP signaling pathway?
Activates Adenylyl Cyclase (AC)
What happens when Gαi/o-GTP is activated?
Inhibits Adenylyl Cyclase (AC) activity
What is the function of β-arrestins in GPCR desensitization and intracellular trafficking?
Facilitate receptor internalization
What is the main role of the free Gβγ dimer in GPCR signaling?
Regulates a host of downstream effectors such as adenylyl cyclase
What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?
Increased protein kinase A (PKA) activation
What is modulated by cAMP in addition to PKA activation?
Phosphoinositide 3 kinases
Which enzyme catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG)?
Phospholipase C-β (PLC-β)
What is the function of IP3 in the IP3/Ca signaling pathway?
Releases Ca2+ from the ER
What is the effect of increased cAMP levels on protein kinase A (PKA) activation?
Increased PKA activation
What is the cellular response to Gαs-GTP stimulation in the cAMP signaling pathway?
Activation of Adenylyl Cyclase (AC) and conversion of ATP to cAMP
What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?
Activation of protein kinase A (PKA) and phosphorylation of multiple downstream effector targets
What is the role of IP3 in the IP3/Ca signaling pathway?
Triggering the release of Ca2+ into the cytoplasm from the endoplasmic reticulum (ER)
What is the function of β-arrestins in GPCR desensitization and intracellular trafficking?
Binding to phosphorylated GPCR and facilitating receptor internalization
What is the primary function of phosphatidylinositol-biphosphate (PIP2) in the IP3/Ca signaling pathway?
Being converted by Phospholipase C-β (PLC-β) to inositol triphosphate (IP3) and diacylglycerol (DAG)
What is the effect of Gαi/o-GTP on the activity of Adenylyl Cyclase (AC) in the cAMP signaling pathway?
Inhibition of the activity of Adenylyl Cyclase (AC) and lowering of cellular cAMP level
What is the primary role of Gαq/11-GTP in the IP3/Ca signaling pathway?
Activating Phospholipase C-β (PLC-β) in the cell membrane
What happens when Gαi/o-GTP is activated in the cAMP signaling pathway?
Inhibition of the activity of Adenylyl Cyclase (AC) and lowering of cellular cAMP level
What is the role of DAG in the IP3/Ca2+ signaling pathway?
Activating protein kinase C (PKC)
What is modulated by cAMP in addition to PKA activation in the cAMP signaling pathway?
The activity of several Guanine Exchange Factors (GEFs) and ion channels
What is the function of phosphatidylinositol-biphosphate (PIP2) in the IP3/Ca signaling pathway?
Cleaved by Gα-GTP activated phospholipase C-β (PLC-β) to generate 2nd messengers
What is the primary function of the free Gβγ dimer in GPCR signaling?
Regulating a host of downstream effectors such as voltage-gated Ca++ channels, inwardly-rectifying K channels, GPCR kinases, phosphoinositide 3 kinases, adenylyl cyclase, phospholipase C-β
What are the 2nd messengers generated by Gα-GTP activated phospholipase C-β (PLC-β)?
Inositol triphosphate (IP3) and Diacylglycerol (DAG)
Which chemical messengers act on α1 receptors?
Norepinephrine and epinephrine
What is the role of β-arrestins in GPCR desensitization and intracellular trafficking?
Binding to phosphorylated GPCR, inhibiting G protein coupling, facilitating receptor internalization, and activating G-protein-independent GPCR signaling cascades
What cellular response is mediated by Gαi/o-GTP in the cAMP signaling pathway?
Inhibits the activity of Adenylyl Cyclase (AC) and lowers cellular cAMP level
What is the function of IP3 in the IP3/Ca signaling pathway?
Diffuses through the cytosol and releases Ca2+ from the ER
What is modulated by cAMP in addition to PKA activation?
Modulates the activity of several Protein Kinase C (PKC)
What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?
Increases PKA activation
What is the role of Gαs-GTP in the cAMP signaling pathway?
Activates Adenylyl Cyclase (AC) and increases cellular cAMP level
What is the role of Gαq/11-GTP in the IP3/Ca signaling pathway?
Activates phospholipase C-β (PLC-β) to generate 2nd messengers
What is the primary role of phospholipase C-β (PLC-β) in the IP3/Ca signaling pathway?
Catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG)
Test your knowledge of the cAMP signalling pathway and G-Protein-Coupled Receptors with this quiz from the MPharm Programme. Topics include Gs-GTP activation of Adenylyl Cyclase, conversion of ATP to cAMP, and downstream effects of PKA activation.
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