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Questions and Answers
Questions and Answers
What is the main function of G protein coupled receptors (GPCRs)?
What is the main function of G protein coupled receptors (GPCRs)?
- To act as molecular switches
- To activate adenylyl cyclase
- To bind to a wide array of molecules (correct)
- To catalyze the formation of cyclic AMP from ATP
How are G proteins activated by GPCRs?
How are G proteins activated by GPCRs?
- Ligand binding changes the confirmation of the receptor, leading to activation of the GPCR (correct)
- Adenylyl cyclase catalyzes the formation of cyclic AMP from ATP
- The alpha subunit dissociates from the beta and gamma subunits, initiating different signaling pathways
- GTP is removed from the alpha subunit of the G protein, causing activation of the G protein
Which subunits are present in trimeric G proteins?
Which subunits are present in trimeric G proteins?
- Omega, pi, and rho
- Delta, epsilon, and zeta
- Alpha, beta, and gamma (correct)
- Mu, nu, and xi
What is the main function of adenylyl cyclase in the context of G protein activation?
What is the main function of adenylyl cyclase in the context of G protein activation?
Where does the alpha and gamma subunits of trimeric G proteins anchor?
Where does the alpha and gamma subunits of trimeric G proteins anchor?
What is the role of cAMP in G protein signaling?
What is the role of cAMP in G protein signaling?
What causes activation of G proteins in the context of GPCR signaling?
What causes activation of G proteins in the context of GPCR signaling?
Which enzyme converts GTP to cGMP as a secondary messenger?
Which enzyme converts GTP to cGMP as a secondary messenger?
What molecule is formed when cAMP is further hydrolysed by cyclic AMP phosphodiesterase?
What molecule is formed when cAMP is further hydrolysed by cyclic AMP phosphodiesterase?
Which G protein family stimulates adenylate cyclase?
Which G protein family stimulates adenylate cyclase?
What activates the Gq/11 family of G proteins?
What activates the Gq/11 family of G proteins?
What is the function of calmodulin when activated by Ca2+?
What is the function of calmodulin when activated by Ca2+?
What is the role of phosphodiesterase when activated by light in the vision process?
What is the role of phosphodiesterase when activated by light in the vision process?
In the vision process, what happens when cGMP levels decrease?
In the vision process, what happens when cGMP levels decrease?
How does an influx of ions across the membrane affect the membrane potential?
How does an influx of ions across the membrane affect the membrane potential?
What is the function of G protein coupled receptors (GPCRs)?
What is the function of G protein coupled receptors (GPCRs)?
How are G proteins activated by GPCR's?
How are G proteins activated by GPCR's?
What is the role of adenylyl cyclase in G protein activation?
What is the role of adenylyl cyclase in G protein activation?
How does an active GPCR affect G proteins?
How does an active GPCR affect G proteins?
What is the main function of trimeric G proteins?
What is the main function of trimeric G proteins?
Where are the alpha and gamma subunits of trimeric G proteins anchored?
Where are the alpha and gamma subunits of trimeric G proteins anchored?
What is the role of Guanine nucleotide exchange factor (GEF) in G protein signaling?
What is the role of Guanine nucleotide exchange factor (GEF) in G protein signaling?
How does cAMP influence gene expression?
How does cAMP influence gene expression?
What is the function of diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3) as second messengers?
What is the function of diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3) as second messengers?
How do G proteins control channel opening?
How do G proteins control channel opening?
What happens when cGMP levels decrease in the vision process?
What happens when cGMP levels decrease in the vision process?
What is the main function of Gq/11 family of G proteins?
What is the main function of Gq/11 family of G proteins?
How does an influx of ions across the membrane affect the membrane potential?
How does an influx of ions across the membrane affect the membrane potential?
What is the function of cyclic AMP phosphodiesterase in the context of cAMP signaling?
What is the function of cyclic AMP phosphodiesterase in the context of cAMP signaling?
Questions and Answers
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Study Notes
Study Notes
G Protein Coupled Receptors (GPCRs)
- GPCRs are a large family of transmembrane receptors that sense molecules outside the cell and activate intracellular signaling pathways
- The main function of GPCRs is to transmit signals from outside the cell to the inside, leading to various cellular responses
G Protein Activation
- G proteins are activated by GPCRs through a conformational change in the receptor, allowing the G protein to bind to the receptor
- Activation of G proteins by GPCRs leads to the exchange of GDP for GTP, causing the G protein to dissociate from the receptor
Trimeric G Proteins
- Trimeric G proteins consist of three subunits: alpha, beta, and gamma
- The alpha subunit binds to GTP, while the beta and gamma subunits are involved in anchoring the G protein to the plasma membrane
- The alpha and gamma subunits of trimeric G proteins anchor to the plasma membrane through lipid modifications
Adenylyl Cyclase and cAMP Signaling
- Adenylyl cyclase is an enzyme that converts ATP to cAMP, a secondary messenger, in response to G protein activation
- cAMP plays a key role in G protein signaling, influencing gene expression, ion channel opening, and other cellular responses
- cAMP is further hydrolyzed by cyclic AMP phosphodiesterase to form 5'-AMP
G Protein Families and Signaling
- The Gs family of G proteins stimulates adenylate cyclase, leading to an increase in cAMP levels
- The Gq/11 family of G proteins activates phospholipase C, leading to the formation of diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3) as second messengers
- The Gi family of G proteins inhibits adenylate cyclase, leading to a decrease in cAMP levels
- Guanine nucleotide exchange factor (GEF) facilitates the exchange of GDP for GTP, activating the G protein
G Protein Signaling and Channels
- G proteins control channel opening by interacting with and modifying the channel proteins
- An influx of ions across the membrane affects the membrane potential, leading to changes in cellular responses
Vision Process
- In the vision process, cGMP is converted from GTP by the enzyme guanylyl cyclase
- cGMP levels decrease in response to light, leading to the closure of ion channels and hyperpolarization of the membrane
- Phosphodiesterase, activated by light, breaks down cGMP, leading to a decrease in cGMP levels
Calmodulin and Phosphodiesterase
- Calmodulin, when activated by Ca2+, activates enzymes involved in the signaling cascade
- Phosphodiesterase, activated by light, breaks down cGMP, leading to a decrease in cGMP levels
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