Cell Signaling
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Questions and Answers

What is the primary function of a receptor protein?

  • To regulate the cytoskeleton structure
  • To metabolize hydrophobic signal molecules
  • To transmit chemical signals from inside the cell to outside the cell
  • To receive chemical signals from outside the cell and activate intracellular signaling pathways (correct)

    • What is the main difference between hydrophilic and hydrophobic signal molecules?

  • Hydrophilic signal molecules are larger than hydrophobic signal molecules
  • Hydrophilic signal molecules can cross the cell membrane, while hydrophobic signal molecules cannot
  • Hydrophilic signal molecules are more potent than hydrophobic signal molecules
  • Hydrophilic signal molecules bind to cell surface receptors, while hydrophobic signal molecules bind to intracellular receptors (correct)

    • What is the function of effector proteins in intracellular signaling pathways?

  • To metabolize signal molecules
  • To process and distribute the signal to specific intracellular targets (correct)
  • To regulate the activity of receptors
  • To receive chemical signals from outside the cell

    • What is the main characteristic of G-protein coupled receptors?

    <p>They are metabotropic receptors that activate G-proteins</p> Signup and view all the answers

    What is the mechanism of action of ligand-gated ion channel receptors?

    <p>They bind to ligands, which directly open ion channels</p> Signup and view all the answers

    What is the location of nuclear receptors?

    <p>In the nucleus or in the cytoplasm</p> Signup and view all the answers

    What is the primary function of the cytosolic domain of a receptor tyrosine kinase?

    <p>To have intrinsic enzyme activity or associate with an enzyme</p> Signup and view all the answers

    What is the result of the binding of a ligand to a receptor tyrosine kinase?

    <p>Dimerization and phosphorylation of the receptor</p> Signup and view all the answers

    Which of the following growth factors acts through a receptor tyrosine kinase?

    <p>Insulin-like growth factor</p> Signup and view all the answers

    What is the mechanism of activation of some receptor tyrosine kinases?

    <p>Conformational changes from the interaction between the two kinase domains</p> Signup and view all the answers

    What is the purpose of phosphotyrosine docking sites in receptor tyrosine kinase signaling?

    <p>To bind to adaptor proteins and relay the signal</p> Signup and view all the answers

    What is the primary function of intracellular receptors?

    <p>To bind to small hydrophobic signal molecules and regulate gene transcription</p> Signup and view all the answers

    Which type of hormones bind to intracellular receptors?

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

    What is the location of intracellular receptors in target cells?

    <p>In both the cytosol and nucleus</p> Signup and view all the answers

    Which of the following drugs targets intracellular receptors?

    <p>All of the above</p> Signup and view all the answers

    What is the result of binding of small hydrophobic signal molecules to intracellular receptors?

    <p>Alteration of gene transcription</p> Signup and view all the answers

    What is the characteristic of lipophilic signals that allows them to enter target cells?

    <p>They are small and hydrophobic</p> Signup and view all the answers

    What is the function of G-protein coupled receptors?

    <p>To mediate most responses to signals from the external world</p> Signup and view all the answers

    What is the function of G-proteins?

    <p>To relay the signal into the cell interior</p> Signup and view all the answers

    What is the function of the α subunit of G-proteins?

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

    What is the function of the β/γ complex of G-proteins?

    <p>To interact with targets</p> Signup and view all the answers

    What is the function of second messengers?

    <p>To diffuse away from their source and spread the signal</p> Signup and view all the answers

    What is the function of protein kinase A (PKA)?

    <p>To bind to and alter the behavior of selected signaling or effector proteins</p> Signup and view all the answers

    Why are GPCRs important in medicine?

    <p>Because almost half of all known drugs work through GPCRs</p> Signup and view all the answers

    What is the primary function of a receptor?

    <p>To receive chemical signals from outside the cell</p> Signup and view all the answers

    What type of receptors are involved in rapid neurotransmission?

    <p>Ligand-gated ion channel receptors</p> Signup and view all the answers

    What is the location of receptors that bind to hydrophilic signal molecules?

    <p>On the cell surface</p> Signup and view all the answers

    What type of receptors are involved in regulating gene expression?

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

    What is the function of effector proteins in intracellular signaling pathways?

    <p>To process and distribute signals to specific targets</p> Signup and view all the answers

    What type of signal molecules bind to intracellular receptors?

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

    Which receptor type is also called ionotropic receptors?

    <p>Ligand-gated ion channel receptors</p> Signup and view all the answers

    What is the primary function of G-proteins?

    <p>To relay the signal into the cell interior</p> Signup and view all the answers

    What is the result of the activation of G-proteins?

    <p>The α subunit exchanges GDP for GTP</p> Signup and view all the answers

    What is the function of cyclic adenosine monophosphate (cAMP)?

    <p>To act as a second messenger</p> Signup and view all the answers

    What is the function of diacylglycerol (DAG)?

    <p>To act as a second messenger</p> Signup and view all the answers

    What is the function of inositol 1,4,5-trisphosphate (IP3)?

    <p>To act as a second messenger</p> Signup and view all the answers

    What is the result of the activation of protein kinase A (PKA)?

    <p>The behavior of selected signaling proteins is altered</p> Signup and view all the answers

    What is the function of Gs (stimulatory) G-proteins?

    <p>To stimulate the cAMP signaling pathway</p> Signup and view all the answers

    How many types of G-proteins are activated by the same signal?

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

    What is the role of lipophilic signal molecules in target cells?

    <p>They diffuse directly across the plasma membrane and bind to intracellular receptors</p> Signup and view all the answers

    Which of the following drugs targets intracellular receptors to decrease blood lipids?

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

    What is the outcome of the binding of small hydrophobic signal molecules to their respective intracellular receptor proteins?

    <p>The receptor protein alters its ability to control the transcription of specific genes</p> Signup and view all the answers

    Which type of receptors are both receptors and intracellular effectors of the signal?

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

    What is the function of intracellular receptors in the regulation of gene transcription?

    <p>They alter the ability of transcription regulators to control gene transcription</p> Signup and view all the answers

    What is the characteristic of intracellular receptors that allows them to function as transcription regulators?

    <p>Their ability to control the transcription of specific genes</p> Signup and view all the answers

    What is the characteristic of receptor tyrosine kinases that distinguishes them from other enzymes?

    <p>They are transmembrane proteins with ligand-binding domain outside the plasma membrane</p> Signup and view all the answers

    What is the result of dimerization of receptor tyrosine kinases?

    <p>Phosphorylation of tyrosine side chains</p> Signup and view all the answers

    What is the role of the cytosolic domain of receptor tyrosine kinases?

    <p>To either have intrinsic enzyme activity or associate with an enzyme</p> Signup and view all the answers

    What is true about the activation of some receptor tyrosine kinases?

    <p>They are activated by both phosphorylation and conformational changes</p> Signup and view all the answers

    Study Notes

    Cell Signaling

    • A protein molecule that receives chemical signals from outside the cell is called a receptor
    • Receptors can be located on the cell surface or inside the cell (cytoplasm or nucleus)
    • Hydrophilic signal molecules bind to receptors on the cell surface, while hydrophobic signal molecules bind to receptors inside the cell

    Cell Surface Receptors

    • There are five types of cell surface receptors:
      • Ligand-gated ion channel receptors (ionotropic)
      • G-protein coupled receptors (metabotropic)
      • Enzyme-coupled receptors
      • Integrins
      • TOLL-like receptors

    G-Protein Coupled Receptors (GPCRs)

    • GPCRs are integral membrane proteins that pass in and out of the plasma membrane multiple times
    • They bind to a particular type of G protein, which relays the signal into the cell interior
    • G proteins are membrane-associated trimeric proteins with three subunits: α, β, and γ
    • When a ligand binds to a GPCR, the G protein dissociates and interacts with targets, such as enzymes or ion channels

    Second Messengers

    • Second messengers are intracellular signaling molecules generated in response to receptor activation
    • They diffuse away from their source and spread the signal to other parts of the cell
    • Important second messengers include:
      • Diacylglycerol (DAG)
      • Cyclic adenosine monophosphate (cAMP)
      • Inositol 1,4,5-trisphosphate (IP3)
      • Calcium (Ca2+)

    GPCR Signaling Pathway

    • GPCRs can activate many different G proteins, which can interact with multiple targets
    • The same signal can activate many different GPCRs
    • GPCRs are important in medicine, with almost half of all known drugs working through GPCRs or their signaling pathways

    Receptor Tyrosine Kinase (RTK)

    • RTKs are the largest class of enzyme-coupled receptors
    • They are transmembrane proteins with ligand-binding domains outside the plasma membrane and cytosolic domains that have intrinsic enzyme activity or associate with an enzyme
    • Growth factors, such as insulin and epidermal growth factor, act through RTKs
    • RTKs dimerize and phosphorylate each other, creating phosphotyrosine docking sites for intracellular signaling proteins

    Intracellular Receptors

    • Intracellular receptors are transcription regulators that bind to lipophilic signal molecules
    • They can be located in the cytosol or nucleus
    • Examples of intracellular receptors include steroid hormones, thyroid hormones, retinoid, and vitamin D
    • Some drugs use intracellular receptors as targets, such as Fibrates, glucocorticoids, and glitazones

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    Related Documents

    Molecular and Cellular Bases of Physiology L03 - Summer 24 PDF

    Description

    Learn about cell signaling, including the location of receptors, types of cell surface receptors, and second messengers like cAMP. Explore how GPCRs and nuclear receptors work.

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