G-protein coupled week 27
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Questions and Answers

Gs-GTP stimulates the activation of Adenylyl Cyclase (AC).

True (A)

The increased cAMP level leads to the inhibition of protein kinase A (PKA).

False (B)

Gi/o-GTP inhibits the activity of Adenylyl Cyclase (AC) and lowers cellular cAMP level.

True (A)

CAMP can also modulate the activity of several Protein Kinase C (PKC).

<p>False (B)</p> Signup and view all the answers

IP3 acts on the endoplasmic reticulum (ER) and triggers the release of Na+ into the cytoplasm.

<p>False (B)</p> Signup and view all the answers

Phospholipase C- (PLC) catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG).

<p>True (A)</p> Signup and view all the answers

The cAMP Signalling Pathway involves Gq/11-GTP and activation of Adenylyl Cyclase (AC).

<p>False (B)</p> Signup and view all the answers

The increased cAMP level leads to decreased PKA activation.

<p>False (B)</p> Signup and view all the answers

Gi/o-GTP activates the activity of Adenylyl Cyclase (AC) and increases cellular cAMP level.

<p>False (B)</p> Signup and view all the answers

Ca2+ modulates the activity of Ca2+-dependent effector proteins.

<p>True (A)</p> Signup and view all the answers

Phosphatidylinositol-biphosphate (PIP2) is cleaved by Gα-GTP activated phospholipase C-β (PLC-β) to generate 2nd messengers IP3 and DAG?

<p>True (A)</p> Signup and view all the answers

IP3 diffuses through the cytosol and releases Ca2+ from the ER, while DAG activates protein kinase C?

<p>True (A)</p> Signup and view all the answers

The free Gβγ dimer plays key roles in GPCR signaling by regulating a host of downstream effectors such as voltage-gated Na+ channels?

<p>False (B)</p> Signup and view all the answers

Desensitization & internalization of GPCRs is controlled by the sequential action of G protein-coupled receptor kinases (GRKs) and cytoplasmic adaptor proteins?

<p>True (A)</p> Signup and view all the answers

β-arrestins bind to phosphorylated GPCR & facilitate receptor internalization?

<p>True (A)</p> Signup and view all the answers

Internalized GPCRs are trafficked to lysosomes for recycling back to the cell surface for future signaling?

<p>False (B)</p> Signup and view all the answers

Norepinephrine and epinephrine act on α1 receptors?

<p>True (A)</p> Signup and view all the answers

Acetylcholine acts on M2 receptors for autonomic nervous system control of heart function?

<p>False (B)</p> Signup and view all the answers

Histamine H1 receptor mediates the actions of histamine?

<p>True (A)</p> Signup and view all the answers

Dopamine D1 and D5 receptors are part of the GPCR receptor superfamily?

<p>True (A)</p> Signup and view all the answers

Serotonin (5-HT) acts on 5-HT4, 5-HT6, and 5-HT7 receptors?

<p>True (A)</p> Signup and view all the answers

GPCRs play a role in mediating autonomic nervous system control of heart function?

<p>True (A)</p> Signup and view all the answers

What is the role of DAG in the IP3/Ca2+ signalling pathway?

<p>It activates protein kinase C (C)</p> Signup and view all the answers

Which enzyme catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG)?

<p>Phospholipase C- (PLC) (D)</p> Signup and view all the answers

What is the function of β-arrestins in GPCR desensitization and intracellular trafficking?

<p>They bind to phosphorylated GPCR &amp; facilitate receptor internalization (C)</p> Signup and view all the answers

Which type of receptor mediates the actions of serotonin (5-HT)?

<p>5-HT4, 5-HT6, and 5-HT7 receptors (A)</p> Signup and view all the answers

What happens when Gi/o-GTP is activated?

<p>It inhibits the activity of Adenylyl Cyclase (AC) (C)</p> Signup and view all the answers

What is the main role of the free Gβγ dimer in GPCR signaling?

<p>It regulates a host of downstream effectors such as voltage-gated Na+ channels (B)</p> Signup and view all the answers

What is the effect of increased cAMP level on protein kinase A (PKA) activation?

<p>It leads to increased PKA activation (A)</p> Signup and view all the answers

What is the role of GRKs in GPCR desensitization?

<p>$4 * 2$ (C)</p> Signup and view all the answers

What are the downstream effectors regulated by the free Gβγ dimer in GPCR signaling?

<p>Voltage-gated Ca++ channels, inwardly-rectifying K channels, GPCR kinases, phosphoinositide 3 kinases, adenylyl cyclase, phospholipase C- (A)</p> Signup and view all the answers

What are the 2nd messengers generated by Gα-GTP activated phospholipase C-?

<p>IP3 and Diacylglycerol (DAG) (C)</p> Signup and view all the answers

What is the role of Gαs-GTP in the cAMP signaling pathway?

<p>Stimulates the activation of Adenylyl Cyclase (AC) (D)</p> Signup and view all the answers

What is the effect of Gαi/o-GTP on the cAMP signaling pathway?

<p>Inhibits the activity of Adenylyl Cyclase (AC) (D)</p> Signup and view all the answers

What is the function of IP3 in the IP3/Ca signaling pathway?

<p>Triggers the release of Ca2+ into the cytoplasm (C)</p> Signup and view all the answers

What is the main role of Phospholipase C-β (PLC-β) in the IP3/Ca signaling pathway?

<p>Triggers the release of Ca2+ into the cytoplasm (A)</p> Signup and view all the answers

What is the cellular response to increased cAMP levels?

<p>Activation of protein kinase A (PKA) and phosphorylation of downstream effector targets (A)</p> Signup and view all the answers

What cellular response is mediated by Gαi/o-GTP in the cAMP signaling pathway?

<p>Inhibition of protein kinase A (PKA) and reduced cellular response (D)</p> Signup and view all the answers

What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?

<p>Phosphorylation of downstream effector targets by protein kinase A (PKA) (C)</p> Signup and view all the answers

What is the primary role of Gq/11-GTP in the IP3/Ca signaling pathway?

<p>Triggers the release of Ca2+ into the cytoplasm (B)</p> Signup and view all the answers

What is the effect of Gs-GTP on the activity of Adenylyl Cyclase (AC)?

<p>Stimulates the activation of Adenylyl Cyclase (AC) (A)</p> Signup and view all the answers

What is modulated by cAMP in addition to PKA activation?

<p>Guanine Exchange Factors (GEFs) and ion channels (C)</p> Signup and view all the answers

What is the role of Gαs-GTP in the cAMP signaling pathway?

<p>Stimulates the activation of Adenylyl Cyclase (AC) (C)</p> Signup and view all the answers

What is modulated by cAMP in addition to PKA activation?

<p>Protein Kinase C (PKC) activity (A)</p> Signup and view all the answers

What is the primary role of Gq/11-GTP in the IP3/Ca signaling pathway?

<p>Activates Phospholipase C- (PLC) (C)</p> Signup and view all the answers

What happens when Gi/o-GTP is activated?

<p>Inhibits the activity of Adenylyl Cyclase (AC) and lowers cellular cAMP level (A)</p> Signup and view all the answers

What is the effect of increased cAMP level on protein kinase A (PKA) activation?

<p>Increases PKA activation (B)</p> Signup and view all the answers

What is modulated by cAMP in addition to PKA activation?

<p>Ca2+-dependent effector proteins activity (A)</p> Signup and view all the answers

What is the role of GRKs in GPCR desensitization?

<p>Facilitate receptor internalization and desensitization (B)</p> Signup and view all the answers

What is the function of IP3 in the IP3/Ca signaling pathway?

<p>Triggers the release of Ca2+ into the cytoplasm (A)</p> Signup and view all the answers

What is the role of DAG in the IP3/Ca2+ signalling pathway?

<p>Modulates the activity of Ca2+-dependent effector proteins (D)</p> Signup and view all the answers

What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?

<p>Activation of multiple downstream effector targets (C)</p> Signup and view all the answers

What is the primary function of phosphatidylinositol-biphosphate (PIP2) in the IP3/Ca signaling pathway?

<p>Generates diacylglycerol (DAG) (B)</p> Signup and view all the answers

What is the role of Gαs-GTP in the cAMP signaling pathway?

<p>Activates Adenylyl Cyclase (AC) (C)</p> Signup and view all the answers

What happens when Gαi/o-GTP is activated?

<p>Inhibits Adenylyl Cyclase (AC) activity (A)</p> Signup and view all the answers

What is the function of β-arrestins in GPCR desensitization and intracellular trafficking?

<p>Facilitate receptor internalization (B)</p> Signup and view all the answers

What is the main role of the free Gβγ dimer in GPCR signaling?

<p>Regulates a host of downstream effectors such as adenylyl cyclase (B)</p> Signup and view all the answers

What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?

<p>Increased protein kinase A (PKA) activation (A)</p> Signup and view all the answers

What is modulated by cAMP in addition to PKA activation?

<p>Phosphoinositide 3 kinases (C)</p> Signup and view all the answers

Which enzyme catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) & diacylglycerol (DAG)?

<p>Phospholipase C-β (PLC-β) (C)</p> Signup and view all the answers

What is the function of IP3 in the IP3/Ca signaling pathway?

<p>Releases Ca2+ from the ER (D)</p> Signup and view all the answers

What is the effect of increased cAMP levels on protein kinase A (PKA) activation?

<p>Increased PKA activation (D)</p> Signup and view all the answers

What is the cellular response to Gαs-GTP stimulation in the cAMP signaling pathway?

<p>Activation of Adenylyl Cyclase (AC) and conversion of ATP to cAMP</p> Signup and view all the answers

What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?

<p>Activation of protein kinase A (PKA) and phosphorylation of multiple downstream effector targets</p> Signup and view all the answers

What is the role of IP3 in the IP3/Ca signaling pathway?

<p>Triggering the release of Ca2+ into the cytoplasm from the endoplasmic reticulum (ER)</p> Signup and view all the answers

What is the function of β-arrestins in GPCR desensitization and intracellular trafficking?

<p>Binding to phosphorylated GPCR and facilitating receptor internalization</p> Signup and view all the answers

What is the primary function of phosphatidylinositol-biphosphate (PIP2) in the IP3/Ca signaling pathway?

<p>Being converted by Phospholipase C-β (PLC-β) to inositol triphosphate (IP3) and diacylglycerol (DAG)</p> Signup and view all the answers

What is the effect of Gαi/o-GTP on the activity of Adenylyl Cyclase (AC) in the cAMP signaling pathway?

<p>Inhibition of the activity of Adenylyl Cyclase (AC) and lowering of cellular cAMP level</p> Signup and view all the answers

What is the primary role of Gαq/11-GTP in the IP3/Ca signaling pathway?

<p>Activating Phospholipase C-β (PLC-β) in the cell membrane</p> Signup and view all the answers

What happens when Gαi/o-GTP is activated in the cAMP signaling pathway?

<p>Inhibition of the activity of Adenylyl Cyclase (AC) and lowering of cellular cAMP level</p> Signup and view all the answers

What is the role of DAG in the IP3/Ca2+ signaling pathway?

<p>Activating protein kinase C (PKC)</p> Signup and view all the answers

What is modulated by cAMP in addition to PKA activation in the cAMP signaling pathway?

<p>The activity of several Guanine Exchange Factors (GEFs) and ion channels</p> Signup and view all the answers

What is the function of phosphatidylinositol-biphosphate (PIP2) in the IP3/Ca signaling pathway?

<p>Cleaved by Gα-GTP activated phospholipase C-β (PLC-β) to generate 2nd messengers</p> Signup and view all the answers

What is the primary function of the free Gβγ dimer in GPCR signaling?

<p>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</p> Signup and view all the answers

What are the 2nd messengers generated by Gα-GTP activated phospholipase C-β (PLC-β)?

<p>Inositol triphosphate (IP3) and Diacylglycerol (DAG)</p> Signup and view all the answers

Which chemical messengers act on α1 receptors?

<p>Norepinephrine and epinephrine</p> Signup and view all the answers

What is the role of β-arrestins in GPCR desensitization and intracellular trafficking?

<p>Binding to phosphorylated GPCR, inhibiting G protein coupling, facilitating receptor internalization, and activating G-protein-independent GPCR signaling cascades</p> Signup and view all the answers

What cellular response is mediated by Gαi/o-GTP in the cAMP signaling pathway?

<p>Inhibits the activity of Adenylyl Cyclase (AC) and lowers cellular cAMP level</p> Signup and view all the answers

What is the function of IP3 in the IP3/Ca signaling pathway?

<p>Diffuses through the cytosol and releases Ca2+ from the ER</p> Signup and view all the answers

What is modulated by cAMP in addition to PKA activation?

<p>Modulates the activity of several Protein Kinase C (PKC)</p> Signup and view all the answers

What is the downstream effect of increased cAMP levels in the cAMP signaling pathway?

<p>Increases PKA activation</p> Signup and view all the answers

What is the role of Gαs-GTP in the cAMP signaling pathway?

<p>Activates Adenylyl Cyclase (AC) and increases cellular cAMP level</p> Signup and view all the answers

What is the role of Gαq/11-GTP in the IP3/Ca signaling pathway?

<p>Activates phospholipase C-β (PLC-β) to generate 2nd messengers</p> Signup and view all the answers

What is the primary role of phospholipase C-β (PLC-β) in the IP3/Ca signaling pathway?

<p>Catalyzes the conversion of phosphatidylinositol 4,5-bisphosphate (PIP2) to inositol triphosphate (IP3) &amp; diacylglycerol (DAG)</p> Signup and view all the answers

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