Metabotropic Receptors and Cell Signaling
16 Questions
3 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of metabotropic receptors?

  • Bind ligands without signal transduction
  • Mediate effects through metabolic processes (correct)
  • Directly open ion channels
  • Act as structural proteins

    • How many transmembrane α-helices do G-protein coupled receptors (GPCRs) typically possess?

  • 7 (correct)
  • 5
  • 9
  • 12

    • What is the role of the third intracellular loop (i3) in GPCRs?

  • It binds ligands directly
  • It varies greatly in length and sequence (correct)
  • It is highly conserved across all receptors
  • It is responsible for receptor dimerization

    • What is a key feature of the structure of metabotropic receptors?

    <p>They include an extracellular N-terminus (C)</p> Signup and view all the answers

    Why is knowledge of cell signalling crucial in biochemistry?

    <p>It helps understand disease processes (C)</p> Signup and view all the answers

    What type of receptors do G-proteins couple to?

    <p>Metabotropic receptors (C)</p> Signup and view all the answers

    What modification near the N-terminus of GPCRs is important for membrane trafficking?

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

    What is the significance of the 865 currently known GPCRs?

    <p>They represent the largest family of receptors (A)</p> Signup and view all the answers

    What effect does disruption of disulphide bonds have on ligand binding?

    <p>Decreases ligand binding capacity (D)</p> Signup and view all the answers

    Replacing cysteine in the C-terminal domain affects which aspect of receptor function?

    <p>G-protein coupling (A)</p> Signup and view all the answers

    Which G-proteins are thought to activate processes linked to different effector molecules?

    <p>Gs, Gi, and Gq (B)</p> Signup and view all the answers

    What initiates the signalling cascade in the fight or flight response?

    <p>Release of adrenaline (C)</p> Signup and view all the answers

    What is the main consequence of the cholera toxin's action on G-protein signaling?

    <p>Permanent activation of adenylate cyclase (D)</p> Signup and view all the answers

    Excess chloride transport into the lumen due to cholera toxin leads to what physiological effect?

    <p>Dehydration due to water loss (C)</p> Signup and view all the answers

    Which pathway is primarily activated by the binding of adrenaline to its receptor?

    <p>cAMP signaling pathway (B)</p> Signup and view all the answers

    What type of protein is produced by the cholera-causing organism Vibrio cholera?

    <p>Hexameric protein (C)</p> Signup and view all the answers

    Flashcards

    Metabotropic Receptors

    Receptors triggering a series of metabolic events, often involving enzyme activation to transduce the signal. They are key players in cellular communication and response.

    G-Protein Coupled Receptors (GPCRs)

    Receptors with seven transmembrane domains that are coupled to G proteins. They represent a large and diverse family of receptors with critical roles in various cellular processes.

    Extracellular N-terminus of GPCRs

    The region extending outside the cell membrane. Often houses the ligand-binding site and plays a crucial role in receptor activation.

    Intracellular C-terminus of GPCRs

    The region extending inside the cell membrane. It interacts with intracellular signaling molecules like G proteins and is vital for initiating the signal transduction pathway.

    Signup and view all the flashcards

    Third Intracellular Loop (i3) of GPCRs

    A highly variable region within the GPCR structure. Its diverse sequence and length contribute to the receptor's specificity and interaction with G proteins.

    Signup and view all the flashcards

    G-Protein

    A molecular switch responsible for relaying signals from activated GPCRs to downstream effectors. They are trimeric proteins with a structure comprising alpha, beta, and gamma subunits.

    Signup and view all the flashcards

    Signal Transduction

    The process by which a signal is transmitted from the outside of the cell to the inside, ultimately leading to a cellular response. Involves a cascade of events starting with receptor activation and culminating in cellular changes.

    Signup and view all the flashcards

    Glycosylation

    A modification process that involves the addition of a carbohydrate molecule to a protein. This modification plays a crucial role in protein folding, stability, and functionality.

    Signup and view all the flashcards

    Ligand Binding Capacity

    The ability of a receptor to bind a ligand, measured by the number of ligand molecules that can bind to the receptor.

    Signup and view all the flashcards

    Disulfide Bond

    A type of covalent bond formed between two cysteine amino acid residues in a protein. This bond is important in stabilizing the protein's structure and function.

    Signup and view all the flashcards

    G Protein-Coupled Receptor (GPCR)

    A type of G protein-coupled receptor that is involved in a variety of signaling pathways, including those involved in the fight-or-flight response.

    Signup and view all the flashcards

    Gs Proteins

    A family of G proteins that activate adenylyl cyclase, an enzyme responsible for producing cyclic AMP (cAMP).

    Signup and view all the flashcards

    Adrenaline

    A hormone produced by the adrenal gland that is involved in the fight-or-flight response. It binds to G protein-coupled receptors on muscle and liver cells, triggering a cascade of events that lead to increased glucose release and heart and breathing rates.

    Signup and view all the flashcards

    Cholera Toxin

    A toxin produced by Vibrio cholerae bacterium that causes severe diarrhoea and dehydration. The toxin disrupts intestinal epithelial cells by modifying G proteins, preventing the inactivation of adenylyl cyclase and leading to excessive cAMP production.

    Signup and view all the flashcards

    Cyclic AMP (cAMP)

    A cyclic nucleotide that acts as a second messenger in many signaling pathways. It is involved in a variety of cellular processes, including glucose metabolism, smooth muscle relaxation, and memory formation.

    Signup and view all the flashcards

    Study Notes

    Metabotropic Receptors

    • Metabotropic receptors are slower but have a longer-lasting effect than ionotropic receptors.
    • They utilize a series of metabolic processes, often involving enzyme activation, to transduce signals.
    • An example of this process is the fight-or-flight response.

    Learning Outcomes

    • Explain the principles of cell signaling and signal transduction.
    • Define metabotropic receptors and G-protein-coupled receptors.
    • Explain the structure of G-protein-coupled receptors and how this impacts their activity.
    • Explain the actions of a G-protein when a ligand binds.
    • Explain GPCR signaling transduction.

    Cell Signaling and Signal Transduction

    • Cell signaling is a crucial aspect of modern biochemistry and cell biology.
    • It's essential for cell-cell communication and coordinated cellular function in all organisms.
    • Understanding cell signaling is crucial for comprehending various diseases, like cancer and diabetes.

    Types of Receptors

    • Receptors can be broadly categorized into ligand-gated ion channels, G-protein-coupled receptors, kinase-linked receptors, and nuclear receptors.
    • Each type of receptor mediates signals differently, impacting cellular responses in various ways.
    • Receptors have diverse time scales for their effects, ranging from milliseconds to hours.

    Receptor Names

    • Metabotropic receptors mediate their effects by activating a series of metabolic processes, usually involving enzyme activation to transduce the signal.
    • 7-transmembrane G-protein-coupled receptors are a specific type and are characterized by their structure and mechanism of transducing chemical signals.

    Type 2: G-protein-coupled Receptors

    • G protein-coupled receptors (GPCRs) are transmembrane receptors, typically spanning the cell membrane seven times.
    • They are composed of 400-500 polypeptide chains.
    • GPCRs employ G proteins to mediate their interactions with intracellular effector systems.
    • This receptor family is one of the largest and is a common therapeutic target for various drugs.

    Structure of GPCRs

    • GPCRs have seven transmembrane α-helices that are largely conserved.
    • The extracellular N-terminus and intracellular C-terminus exhibit variation in length and sequence.
    • The third intracellular loop is highly variable.

    Modifications to GPCR Structure

    • Glycosylation, with carbohydrates bonded near the N-terminus, plays a critical role in membrane traffic and insertion, but not in ligand binding.

    Ligand Binding Capacity

    • Disulfide bonds connect cysteines in loops E2 and E3.
    • Disruption of these bonds can reduce ligand binding capacity.

    Effectiveness of Cellular Response

    • Cysteine residues in the C-terminal domain stabilize receptor-membrane interactions.
    • Replacing these cysteines doesn't affect ligand binding but may reduce G-protein coupling.

    Protein Coupling

    • Different G protein subtypes exist.
    • The α-subunit largely determines the subtype (e.g., G₂, G₁, Gq, or G₁₃).

    Type 2: G protein-coupled Receptors

    • Different G proteins activate different effector molecules, like enzymes and ion channels.
    • Examples include adenylyl cyclase and phospholipase C.
    • Alpha subunits define the subtypes (Gs, G₁, Gq, or G₁₃).

    Signaling Pathway Involving Second Messengers IP₃ and Ca²⁺

    • Signaling pathways trigger responses like changes in cell metabolism, activation of gene activity, or opening or closure of ion channels.
    • Second messengers like IP₃ and Ca²⁺ are involved in these processes.

    Fight-or-Flight Pathway

    • Adrenaline, a hormone released by the adrenal gland, plays a key role in the fight-or-flight response.

    • It travels through the bloodstream to muscle and liver cells and binds to G protein-coupled receptors.

    • The binding triggers a cascade of events that result in glucose release to prepare the body for action.

    Disease Associated with G-proteins (Cholera)

    • Vibrio cholera toxin affects intestinal epithelial cells.
    • Beta subunits of the toxin attach to the cells, and alpha subunits activate adenylyl cyclase.
    • High cAMP levels lead to chloride transport into the lumen and sodium absorption.
    • These processes result in water loss.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Metabotropic Receptors Lecture Notes PDF

    Description

    This quiz explores the principles of cell signaling and the role of metabotropic receptors in signal transduction. You'll learn about G-protein-coupled receptors, their structure, and their impact on cellular functions. Understanding these concepts is vital for grasping their implications in various diseases.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser