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Questions and Answers
What primarily dictates a cell's response to signals?
What primarily dictates a cell's response to signals?
Which of the following best describes the role of second messengers?
Which of the following best describes the role of second messengers?
What is a key characteristic of synaptic connections regarding receptor specificity?
What is a key characteristic of synaptic connections regarding receptor specificity?
What role do modular interaction domains play in signaling pathways?
What role do modular interaction domains play in signaling pathways?
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How do G proteins contribute to signal amplification?
How do G proteins contribute to signal amplification?
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What is involved in creating a concentrated signaling microenvironment?
What is involved in creating a concentrated signaling microenvironment?
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Why is specificity important in cellular signaling?
Why is specificity important in cellular signaling?
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Which combination of domains binds to phosphorylated tyrosine?
Which combination of domains binds to phosphorylated tyrosine?
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What is the main role of cyclic AMP (cAMP) in signal transduction?
What is the main role of cyclic AMP (cAMP) in signal transduction?
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How does epinephrine affect blood sugar levels in the body?
How does epinephrine affect blood sugar levels in the body?
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Which of the following topics describes the process of cellular signal desensitization?
Which of the following topics describes the process of cellular signal desensitization?
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What is a common feature of G protein-coupled receptors (GPCRs)?
What is a common feature of G protein-coupled receptors (GPCRs)?
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What type of signaling pathway has been linked to Basal Cell Carcinoma in relation to the Hedgehog pathway?
What type of signaling pathway has been linked to Basal Cell Carcinoma in relation to the Hedgehog pathway?
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Which of the following statements best describes the function of G proteins in cell signaling?
Which of the following statements best describes the function of G proteins in cell signaling?
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Which mechanism is involved when cells turn off pathways in the absence of ligands?
Which mechanism is involved when cells turn off pathways in the absence of ligands?
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What is the primary function of CaM-kinase II in relation to Ca2+ oscillations?
What is the primary function of CaM-kinase II in relation to Ca2+ oscillations?
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What does the activation of the Hedgehog signaling pathway typically result in?
What does the activation of the Hedgehog signaling pathway typically result in?
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How many olfactory receptors are estimated to be present in humans?
How many olfactory receptors are estimated to be present in humans?
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What initiates action potential firing in olfactory receptor cells?
What initiates action potential firing in olfactory receptor cells?
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What allows the detection of a wide variety of odors?
What allows the detection of a wide variety of odors?
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What role do RGS proteins play in G-protein signaling?
What role do RGS proteins play in G-protein signaling?
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How are G-protein coupled receptors characterized in terms of structure?
How are G-protein coupled receptors characterized in terms of structure?
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Which second messenger is NOT typically generated by G-protein signaling?
Which second messenger is NOT typically generated by G-protein signaling?
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What aspect of signal amplification is crucial in G-protein coupled receptor pathways?
What aspect of signal amplification is crucial in G-protein coupled receptor pathways?
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What is the primary enzyme target of the Gs protein?
What is the primary enzyme target of the Gs protein?
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What is the role of Protein Kinase A (PKA) in cellular signaling?
What is the role of Protein Kinase A (PKA) in cellular signaling?
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Which process is primarily regulated by CREB proteins in the context of PKA activity?
Which process is primarily regulated by CREB proteins in the context of PKA activity?
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What main issue does cholera create in the body?
What main issue does cholera create in the body?
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How does adenylyl cyclase activity change in response to Gs protein activation?
How does adenylyl cyclase activity change in response to Gs protein activation?
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How does cholera toxin affect the trimeric Gs a-subunit?
How does cholera toxin affect the trimeric Gs a-subunit?
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What is the primary function of cyclic-AMP phosphodiesterase (PDE)?
What is the primary function of cyclic-AMP phosphodiesterase (PDE)?
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What is the function of the cystic fibrosis transmembrane conductance regulator (CFTR)?
What is the function of the cystic fibrosis transmembrane conductance regulator (CFTR)?
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What is the most common mutation in CFTR linked to?
What is the most common mutation in CFTR linked to?
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What is a significant difference in response to cAMP in various cell types largely attributed to?
What is a significant difference in response to cAMP in various cell types largely attributed to?
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Why is cystic fibrosis (CF) considered one of the most common fatal inherited diseases?
Why is cystic fibrosis (CF) considered one of the most common fatal inherited diseases?
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What is the purpose of serine/threonine phosphoprotein phosphatases in cellular signaling?
What is the purpose of serine/threonine phosphoprotein phosphatases in cellular signaling?
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Which of these therapies involves RGS proteins?
Which of these therapies involves RGS proteins?
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Which enzyme is associated with the signaling pathway involving phospholipase C-b?
Which enzyme is associated with the signaling pathway involving phospholipase C-b?
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What does a mutation in the CFTR gene primarily lead to?
What does a mutation in the CFTR gene primarily lead to?
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What concept explains how carriers of certain autosomal recessive diseases might gain an advantage against other diseases?
What concept explains how carriers of certain autosomal recessive diseases might gain an advantage against other diseases?
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What is the primary function of nuclear hormone receptors?
What is the primary function of nuclear hormone receptors?
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How long do nitric oxide (NO) gas signals typically last in the system?
How long do nitric oxide (NO) gas signals typically last in the system?
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Which signaling type is important for development and often has a short range?
Which signaling type is important for development and often has a short range?
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What characterizes receptors in slower intercellular signaling?
What characterizes receptors in slower intercellular signaling?
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In terms of numbers, how many nuclear hormone receptors are found in humans?
In terms of numbers, how many nuclear hormone receptors are found in humans?
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Which of the following is NOT a type of receptor mentioned for cell-cell signaling?
Which of the following is NOT a type of receptor mentioned for cell-cell signaling?
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What type of signaling is characterized by long-range communication and is essential for homeostasis?
What type of signaling is characterized by long-range communication and is essential for homeostasis?
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What is a characteristic of smooth muscle responses to nitric oxide signaling?
What is a characteristic of smooth muscle responses to nitric oxide signaling?
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Study Notes
Cell Signaling Overview
- Cell-cell signaling is ancient and diverse, serving various cooperative functions.
- Cell context, second messengers, molecular switches, cascade amplification, and pathway regulation are crucial.
G-Protein Coupled Receptors (GPCRs)
- GPCRs are a large family of receptors that employ trimeric G proteins.
- They play a role in turning off G proteins, activating adenylyl cyclase/cAMP, and PKA signaling pathways.
- Also involved in IP3, phospholipase C-β, and Ca²⁺-mediated signaling. Olfaction is another example.
Cell Signaling Examples
- Mating factor in S. cerevisiae is an ancient example of cell signaling.
- Bacterial films exhibit electrical signaling.
- Dictyostelium discoideum uses cAMP for chemotaxis.
- Nitric oxide (NO) gas signals to smooth muscle, expanding blood vessels, and lowering blood pressure.
Cell Signaling Principles
- Proteins, peptides, amino acids, nucleotides, steroids, retinoids, dissolved gases, light, touch, and heat are involved in cell signaling. Exocytosis and transmembrane transport are key methods.
Cell Signaling Pathway Characteristics
- GPCRs, ion channels, and enzyme-coupled receptors are involved in intercellular signal pathways.
- Nuclear hormone receptors mediate nitric oxide (NO) signaling, responding rapidly (5-10 seconds).
Types of Intercellular Signaling
- Short Range: Contact-dependent, cell-to-cell signaling (e.g., immune system).
- Long Range: Synaptic signaling between neurons and endocrine signaling through the bloodstream.
- Autocrine: A signaling molecule acts on the same cell that produced it.
- Paracrine: A signaling molecule acts on nearby cells.
Intracellular Signaling
- Signaling molecules cross the cell membrane or trigger a cascade within the cell, altering protein function, gene expression, and/or cellular behavior.
Pathway Activation Regulation
- Pathways have mechanisms to turn themselves off when ligands are absent. Hedgehog pathway is an example.
- Desensitization occurs by negative feedback, delayed feed-forward, receptor inactivation, receptor sequestration, and receptor destruction.
- These are critical for normal cellular function and in response to uncontrolled signaling pathways like cancer. Inhibitors of pathways are also key.
G-Protein Linked/Coupled Receptors
- Many signaling molecules are mediated by these receptors, including hormones, photons, neurotransmitters, peptides, amino acids, nucleotides, and fatty acids.
Second Messengers
- cAMP, Ca²⁺, and diacylglycerol are second messengers generated in response to receptor activation and quickly diffuse, amplifying the signal throughout the cell.
Specific Systems (e.g., cAMP and PKA)
- Adenylyl cyclase/cAMP and PKA are crucial in hormone and neurotransmitter signaling.
- PKA has rapid responses and affects several target proteins in different cells (e.g., CFTR).
- It is important for short-term responses.
cAMP Signaling
- Some hormone-induced responses are mediated by cAMP and subsequently PKA, including influencing thyroid hormone synthesis/secretion and various processes (e.g., bone resorption). Specific responses depend on the cell.
Cholera Toxin
- Cholera toxin locks trimeric G proteins Gs α-subunits in the active state.
- This leads to high and prolonged cAMP levels linked to severe dehydration.
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)
- CFTR is a chloride channel altered by the cholera toxin via cAMP signaling affected by the high levels of cAMP.
- The abnormal function of CFTR leads to cystic fibrosis and is linked to other illnesses via its involvement in the signaling pathway.
Intracellular Signaling Molecules
- Signaling proteins act as 'switches'.
- These molecules can utilize different mechanisms, like phosphorylation or GTP binding.
- These allow signal sensitivity and strength changes.
Other Signal Transduction Pathway Components
- GPCRs are vital in olfaction and other physiological processes.
- Olfactory receptors are highly unique for each odor.
- Intracellular Ca2+ signaling regulates and is a critical element for many cellular processes.
- Ca2+ oscillations are critical in cells’ response.
- Pathways use various techniques for desensitization, including receptor inactivation, sequestration and destruction including negative feedback.
Specific Receptor Signaling
- Receptor tyrosine kinases (RTKs) and nuclear hormone receptors are implicated in different signaling pathways.
- Other key signaling pathways such as Wnt, TGF-β, Hedgehog (Hh), Jak/STAT, and Notch are involved in particular functions.
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Description
Explore the diverse and ancient world of cell signaling, focusing on the role of G-Protein Coupled Receptors (GPCRs). Understand how these receptors interact with G proteins, second messengers, and contribute to vital physiological processes. Discover examples from yeast mating to bacterial electrical signaling.
