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G-Protein Coupled Receptors (GPCRs) in Eukaryotes
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G-Protein Coupled Receptors (GPCRs) in Eukaryotes

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@MesmerizedElder

Questions and Answers

Where are G-protein coupled receptors typically found?

  • Viruses
  • Prokaryotes
  • Eukaryotes (correct)
  • Fungi

    • What percentage of modern medicinal drugs target GPCRs?

  • 30 to 50% (correct)
  • 10 to 20%
  • 50 to 70%
  • 20 to 30%

    • What is unique about the structure of GPCRs?

  • They have nine transmembrane alpha sheets
  • They have seven transmembrane alpha helices (correct)
  • They have three transmembrane beta helices
  • They have five transmembrane beta sheets

    • What is another name for GPCRs based on their structure?

    <p>7 transmembrane receptors</p> Signup and view all the answers

    What is the function of GPCRs in the body?

    <p>They regulate a variety of physiological processes</p> Signup and view all the answers

    What type of compounds can bind to GPCRs?

    <p>A wide range of compounds, including light sensitive compounds, odors, pheromones, hormones, and neurotransmitters</p> Signup and view all the answers

    What is the significance of GPCRs in research?

    <p>Many G-proteins and GPCRs still have unknown functions</p> Signup and view all the answers

    What award was given for research on GPCRs in 2012?

    <p>Nobel Prize in Chemistry</p> Signup and view all the answers

    What is the primary function of G-proteins?

    <p>To bind GTP and GDP</p> Signup and view all the answers

    What is the composition of G-proteins associated with GPCRs?

    <p>Heterotrimeric (three subunits)</p> Signup and view all the answers

    What is the purpose of lipid anchors in G-proteins?

    <p>To attach to the cell membrane</p> Signup and view all the answers

    What is the result of a G-protein binding GTP?

    <p>The G-protein dissociates from the beta and gamma subunits</p> Signup and view all the answers

    What is the role of the GPCR in the signaling pathway?

    <p>To respond to signaling molecules</p> Signup and view all the answers

    What is the result of the ligand binding to the GPCR?

    <p>The GPCR undergoes a conformational change</p> Signup and view all the answers

    What is the function of the alpha subunit in the signaling pathway?

    <p>To exchange GDP for GTP</p> Signup and view all the answers

    What is the purpose of the beta and gamma subunits in the signaling pathway?

    <p>To form a dimer with the alpha subunit</p> Signup and view all the answers

    What is the ultimate outcome of the G-protein signaling pathway?

    <p>The alpha subunit regulates protein function</p> Signup and view all the answers

    What is the order of the steps in the G-protein signaling pathway?

    <p>Ligand binds to GPCR, GPCR undergoes conformational change, alpha subunit exchanges GDP for GTP, alpha subunit dissociates and regulates target proteins</p> Signup and view all the answers

    What occurs when the alpha subunit binds to a target protein?

    <p>The target protein relays a signal</p> Signup and view all the answers

    What is the result of the hydrolysis of GTP to GDP?

    <p>The process returns to its normal state</p> Signup and view all the answers

    What is the role of the RGS protein?

    <p>To accelerate the hydrolysis of GTP to GDP</p> Signup and view all the answers

    What is the function of adenylate cyclase?

    <p>To produce cAMP from ATP</p> Signup and view all the answers

    What is the effect of cyclic AMP on the body?

    <p>It increases heart rate and dilates skeletal muscle blood vessels</p> Signup and view all the answers

    What happens to the alpha subunit when the GTP is hydrolyzed to GDP?

    <p>It returns to its original state</p> Signup and view all the answers

    What is the role of the beta-gamma subunits?

    <p>To interact with other proteins to relay messages</p> Signup and view all the answers

    What is the result of the binding of epinephrine to the adrenergic receptor?

    <p>The GPCR undergoes a conformational change</p> Signup and view all the answers

    What is the purpose of the G-protein signaling pathway?

    <p>To transmit signals from outside the cell to inside the cell</p> Signup and view all the answers

    What is the final result of the G-protein signaling pathway?

    <p>The transmission of signals from outside the cell to inside the cell</p> Signup and view all the answers

    Study Notes

    G-Protein Coupled Receptors (GPCRs)

    • GPCRs are only found in eukaryotes and comprise the largest known class of membrane receptors.
    • There are over 1,000 known different types of GPCRs in humans, each specific to a particular function.

    Structure of GPCRs

    • GPCRs have seven transmembrane alpha helices, which is a unique and important characteristic.
    • They are often also referred to as "7 transmembrane receptors" due to this structural feature.

    Interaction with G-Proteins

    • GPCRs interact with G-proteins, which are specialized proteins that can bind GTP and GDP.
    • The G-proteins that associate with GPCRs are heterotrimeric, meaning they have three different subunits: alpha, beta, and gamma.

    Signaling Pathway

    • The signaling pathway of GPCRs involves a ligand binding to the receptor, causing a conformational change.
    • The conformational change triggers the exchange of GDP for GTP on the alpha subunit, which then dissociates and regulates target proteins.
    • The alpha subunit and beta-gamma dimer can interact with other proteins to relay messages, leading to a range of downstream effects.

    Steps of the Signaling Pathway

    • Step 1: Ligand binds to the GPCR
    • Step 2: GPCR undergoes a conformational change
    • Step 3: Alpha subunit exchanges GDP for GTP
    • Step 4: Alpha subunit dissociates and regulates target proteins
    • Step 5: Target protein relays a signal, leading to a range of downstream effects
    • Step 6: GTP is hydrolyzed to GDP, returning the system to its original state

    Regulation of G-Protein Signaling

    • The system can be regulated by RGS proteins, which accelerate the hydrolysis of GTP to GDP.

    Example of GPCR Function

    • The binding of epinephrine (adrenaline) to an adrenergic receptor (a type of GPCR) triggers a signaling pathway that leads to an increase in heart rate, dilation of skeletal muscle blood vessels, and breakdown of glycogen to glucose.

    Importance of GPCRs

    • GPCRs are a large and diverse family of cell surface receptors that respond to many different external signals.
    • They play a crucial role in regulating a wide range of bodily functions, including sensation, growth, and hormone response.

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    Description

    Learn about G-protein coupled receptors, their structure, function, and importance in medicinal drugs. Found only in eukaryotes, they comprise the largest class of membrane receptors.

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