Cell Signaling Overview and GPCRs
48 Questions
0 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 primarily dictates a cell's response to signals?

  • The surrounding environment only
  • The receptors it expresses and the intracellular context (correct)
  • The age of the cell
  • The type of membrane it has

Which of the following best describes the role of second messengers?

  • They only function in the absence of receptors
  • They inhibit receptor activation
  • They are exclusively responsible for fast signaling
  • They are generated in large numbers in response to receptor activation (correct)

What is a key characteristic of synaptic connections regarding receptor specificity?

  • Receptors can only respond to one type of signal
  • Receptor specificity depends solely on the receptor type
  • All receptors must have high affinity
  • Specificity is achieved through connections even when using the same neurotransmitter (correct)

What role do modular interaction domains play in signaling pathways?

<p>They mediate interactions between proteins (A)</p> Signup and view all the answers

How do G proteins contribute to signal amplification?

<p>They act as molecular switches allowing sensitivity to signal strength (C)</p> Signup and view all the answers

What is involved in creating a concentrated signaling microenvironment?

<p>Clustering of receptors and signaling molecules (A)</p> Signup and view all the answers

Why is specificity important in cellular signaling?

<p>It ensures the correct cellular response to various signals (C)</p> Signup and view all the answers

Which combination of domains binds to phosphorylated tyrosine?

<p>SH2 and PTB domains (C)</p> Signup and view all the answers

What is the main role of cyclic AMP (cAMP) in signal transduction?

<p>To serve as a second messenger that amplifies signals (D)</p> Signup and view all the answers

How does epinephrine affect blood sugar levels in the body?

<p>By converting glycogen to glucose (D)</p> Signup and view all the answers

Which of the following topics describes the process of cellular signal desensitization?

<p>Inhibition of the Hedgehog signaling pathway (B)</p> Signup and view all the answers

What is a common feature of G protein-coupled receptors (GPCRs)?

<p>They consist of seven transmembrane domains (C)</p> Signup and view all the answers

What type of signaling pathway has been linked to Basal Cell Carcinoma in relation to the Hedgehog pathway?

<p>Loss of function mutations in Patched gene (C)</p> Signup and view all the answers

Which of the following statements best describes the function of G proteins in cell signaling?

<p>They activate enzymes that produce second messengers (D)</p> Signup and view all the answers

Which mechanism is involved when cells turn off pathways in the absence of ligands?

<p>Receptor internalization and desensitization (C)</p> Signup and view all the answers

What is the primary function of CaM-kinase II in relation to Ca2+ oscillations?

<p>It decodes frequency of different Ca2+ oscillations. (B)</p> Signup and view all the answers

What does the activation of the Hedgehog signaling pathway typically result in?

<p>Increased cell proliferation and differentiation (A)</p> Signup and view all the answers

How many olfactory receptors are estimated to be present in humans?

<p>350 (B)</p> Signup and view all the answers

What initiates action potential firing in olfactory receptor cells?

<p>Formation of cAMP by receptor. (D)</p> Signup and view all the answers

What allows the detection of a wide variety of odors?

<p>The interaction of multiple odorants with various receptors. (C)</p> Signup and view all the answers

What role do RGS proteins play in G-protein signaling?

<p>They deactivate G-proteins as GAPs. (D)</p> Signup and view all the answers

How are G-protein coupled receptors characterized in terms of structure?

<p>They span the membrane seven times. (C)</p> Signup and view all the answers

Which second messenger is NOT typically generated by G-protein signaling?

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

What aspect of signal amplification is crucial in G-protein coupled receptor pathways?

<p>Regulation by cell context. (B)</p> Signup and view all the answers

What is the primary enzyme target of the Gs protein?

<p>Adenylyl cyclase (D)</p> Signup and view all the answers

What is the role of Protein Kinase A (PKA) in cellular signaling?

<p>It phosphorylates proteins on serine or threonine residues. (B)</p> Signup and view all the answers

Which process is primarily regulated by CREB proteins in the context of PKA activity?

<p>Long-term memory formation (D)</p> Signup and view all the answers

What main issue does cholera create in the body?

<p>High levels of dehydration (D)</p> Signup and view all the answers

How does adenylyl cyclase activity change in response to Gs protein activation?

<p>Increases cyclic AMP synthesis by 10-20 fold (B)</p> Signup and view all the answers

How does cholera toxin affect the trimeric Gs a-subunit?

<p>It locks the subunit in the active state. (D)</p> Signup and view all the answers

What is the primary function of cyclic-AMP phosphodiesterase (PDE)?

<p>To hydrolyze cyclic AMP, regulating its levels (A)</p> Signup and view all the answers

What is the function of the cystic fibrosis transmembrane conductance regulator (CFTR)?

<p>To facilitate chloride ion transport across cell membranes. (D)</p> Signup and view all the answers

What is the most common mutation in CFTR linked to?

<p>Resistance to cholera and diarrhea. (A)</p> Signup and view all the answers

What is a significant difference in response to cAMP in various cell types largely attributed to?

<p>Different substrate availability for PKA (C)</p> Signup and view all the answers

Why is cystic fibrosis (CF) considered one of the most common fatal inherited diseases?

<p>Due to high mutation rates and extensive carrier populations. (C)</p> Signup and view all the answers

What is the purpose of serine/threonine phosphoprotein phosphatases in cellular signaling?

<p>To reverse phosphorylations catalyzed by kinases (D)</p> Signup and view all the answers

Which of these therapies involves RGS proteins?

<p>Enhancement of hydrolysis of G proteins. (D)</p> Signup and view all the answers

Which enzyme is associated with the signaling pathway involving phospholipase C-b?

<p>Inositol phospholipid signaling (C)</p> Signup and view all the answers

What does a mutation in the CFTR gene primarily lead to?

<p>Accumulation of thick mucus due to impaired chloride movement. (B)</p> Signup and view all the answers

What concept explains how carriers of certain autosomal recessive diseases might gain an advantage against other diseases?

<p>Heterozygote advantage. (D)</p> Signup and view all the answers

What is the primary function of nuclear hormone receptors?

<p>To act as both receptors and effectors (A)</p> Signup and view all the answers

How long do nitric oxide (NO) gas signals typically last in the system?

<p>5-10 seconds (C)</p> Signup and view all the answers

Which signaling type is important for development and often has a short range?

<p>Paracrine signaling (D)</p> Signup and view all the answers

What characterizes receptors in slower intercellular signaling?

<p>They require longer time to exert effects (A)</p> Signup and view all the answers

In terms of numbers, how many nuclear hormone receptors are found in humans?

<p>48 (A)</p> Signup and view all the answers

Which of the following is NOT a type of receptor mentioned for cell-cell signaling?

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

What type of signaling is characterized by long-range communication and is essential for homeostasis?

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

What is a characteristic of smooth muscle responses to nitric oxide signaling?

<p>They involve the receptor guanylyl cyclase (A)</p> Signup and view all the answers

Flashcards

Signal Reception Locations

Cell-cell signaling pathways occur in multiple places within the cell, including ion channel receptors, G protein-coupled receptors, enzyme-coupled receptors, and nuclear hormone receptors.

Nitric Oxide (NO) Receptor

NO gas, a signaling molecule with a very short half-life (5-10 seconds), affects smooth muscle and nerves.

Guanylyl Cyclase

A protein that acts as both a receptor and signaling molecule, often in connection with nitric oxide (NO).

Nuclear Hormone Receptors

Small, hydrophobic molecules that bind to receptors inside the nucleus. These receptors act as both receptors and effectors in the cell.

Signup and view all the flashcards

Short-Range Signaling

Signaling pathways used in close proximity (e.g., immune system responses and development).

Signup and view all the flashcards

Long-Range Signaling

Signaling crucial for large organisms, facilitating homeostasis.

Signup and view all the flashcards

Autocrine Signaling

A type of signaling where a cell releases a signal that affects itself.

Signup and view all the flashcards

Intercellular Signaling

Forms of communication between cells, categorized by their range.

Signup and view all the flashcards

Cell Response to Signals

The response of a cell to a signal is determined by the receptors it expresses and the intracellular environment of the cell. The specific transcription factors present in different cells also play a significant role during development.

Signup and view all the flashcards

Intracellular Signaling Complex

A cluster of interacting proteins that bind together, often acting as scaffolds or adaptors and facilitating signal amplification.

Signup and view all the flashcards

Signal Amplification

The process by which a signal is amplified within a cell, often through the use of second messengers or a cascade of protein interactions.

Signup and view all the flashcards

Modular Interaction Domains

Specific protein domains that mediate interactions between proteins, often facilitating signal transduction.

Signup and view all the flashcards

SH2 Domain

A protein domain that binds to phosphorylated tyrosine residues.

Signup and view all the flashcards

SH3 Domain

A protein domain that binds to proline-rich regions in other proteins.

Signup and view all the flashcards

Signal Microenvironment

A concentrated area where signaling molecules and receptors are clustered, enhancing signal transduction efficiency.

Signup and view all the flashcards

Second Messengers

Small molecules that relay and amplify the signal within the cell, often generated in large numbers in response to receptor activation.

Signup and view all the flashcards

cAMP

A type of second messenger that is often activated by epinephrine and plays a crucial role in numerous cellular processes like glycogen breakdown.

Signup and view all the flashcards

Epinephrine's Role

Epinephrine, a hormone, binds to receptors on the cell surface and triggers the production of cAMP, initiating a signaling cascade leading to responses like increased heart rate and blood glucose levels.

Signup and view all the flashcards

Pathways Regulation

Cellular signaling pathways are tightly controlled, ensuring that they are activated only when needed and switched off promptly to maintain proper function.

Signup and view all the flashcards

Desensitization

Cells can become desensitized to constant signals, preventing excessive or inappropriate responses. This can happen at various stages of the signaling pathway.

Signup and view all the flashcards

Hedgehog Pathway

A signaling pathway crucial for development, often disrupted in cancers, impacting cell growth and differentiation.

Signup and view all the flashcards

Cyclopamine

A molecule that inhibits the Hedgehog pathway, potentially useful as a therapeutic target for certain cancers.

Signup and view all the flashcards

What does cholera toxin do?

Cholera toxin locks the alpha subunit of the Gs protein in its active state, preventing its inactivation, and causing persistent high levels of cAMP.

Signup and view all the flashcards

Why is cholera so dangerous?

Cholera leads to rapid dehydration and potential death within hours of symptom onset due to the unchecked activity of the Gs protein and its downstream effects.

Signup and view all the flashcards

How does cholera affect CFTR?

Cholera toxin requires functional CFTR (cystic fibrosis transmembrane conductance regulator) to exert its effects. The toxin disrupts the normal balance of electrolytes and water movement, leading to severe diarrhea.

Signup and view all the flashcards

CFTR: Function & Importance

CFTR is an ABC transporter crucial for transporting chloride ions across cell membranes. This movement of chloride ions drives sodium and water movement, vital for moistening the lungs and intestines.

Signup and view all the flashcards

CFTR Mutations

Mutations in the CFTR gene are common and can lead to cystic fibrosis, a serious inherited disease. These mutations disrupt CFTR function, leading to thick mucus and impaired lung function.

Signup and view all the flashcards

Heterozygote Advantage in CF Carriers

Carriers of a mutated CFTR gene may be less susceptible to cholera and other diarrheal diseases. This is because the mutated CFTR protein hinders the cholera toxin's ability to function properly.

Signup and view all the flashcards

RGS Protein Function

RGS (regulator of G protein signaling) proteins accelerate the hydrolysis of GTP bound to the alpha subunit of G proteins, inactivating the G protein and switching off the signal.

Signup and view all the flashcards

Importance of Turning Off G Proteins

G protein signaling needs to be tightly regulated to ensure proper cellular function. Dysregulation can lead to serious health problems, as seen in cholera.

Signup and view all the flashcards

What is adenylyl cyclase?

Adenylyl cyclase is a transmembrane enzyme that converts ATP to cAMP, a second messenger molecule, upon activation by G proteins.

Signup and view all the flashcards

How does cAMP affect the cell?

cAMP activates protein kinase A (PKA) which then phosphorylates other proteins, leading to various downstream effects.

Signup and view all the flashcards

What does PKA do?

Protein kinase A (PKA) phosphorylates serine or threonine residues on its target proteins, altering their activity or function.

Signup and view all the flashcards

How is PKA activity localized?

PKA is often anchored to specific subcellular compartments through anchoring proteins (AKAPs), concentrating its activity in certain areas.

Signup and view all the flashcards

What is phospholipase C-beta (PLC-b)?

PLC-b is an enzyme that hydrolyzes phosphatidylinositol bisphosphate (PIP2) into two signaling molecules: diacylglycerol (DAG) and inositol triphosphate (IP3).

Signup and view all the flashcards

What does IP3 do?

IP3 binds to receptors on the endoplasmic reticulum, triggering the release of calcium ions (Ca2+) into the cytoplasm.

Signup and view all the flashcards

What is the role of calcium (Ca2+)?

Calcium ions are important second messengers that act as intracellular signals, triggering various cellular processes.

Signup and view all the flashcards

What is the difference between rapid and slow PKA responses?

Rapid PKA responses are immediate, like the opening of ion channels, while slow responses involve changes in gene expression and can lead to long-term changes.

Signup and view all the flashcards

CaM-kinase II

A calcium-calmodulin dependent protein kinase that plays a vital role in regulating neuronal functions. It is activated by calcium ions and calmodulin and can phosphorylate various proteins involved in neuronal signaling.

Signup and view all the flashcards

Olfactory Receptors

Specialized G-protein coupled receptors (GPCRs) located in olfactory receptor cells of the nasal epithelium, responsible for detecting different odors.

Signup and view all the flashcards

How do we detect so many smells?

We can detect a vast range of odors because most scents activate multiple olfactory receptors, creating a unique code for each smell. It's like a 'fingerprint' for each odor.

Signup and view all the flashcards

G-protein coupled receptors (GPCRs)

A large family of cell surface receptors that sense a wide variety of stimuli, including light, odors, hormones, and neurotransmitters.

Signup and view all the flashcards

Adenyl cyclase and PLC-b

Enzymes regulated by G-proteins. Adenyl cyclase produces cAMP, a second messenger, while PLC-b breaks down PIP2 into IP3 and DAG.

Signup and view all the flashcards

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.

Studying That Suits You

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

Quiz Team

Related Documents

Lecture 17 - Cell Signaling - Bio 220 PDF

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.

More Like This

Mechanism of Action of Peptide Hormones
18 questions

Mechanism of Action of Peptide Hormones

NourishingFluorine avatar
NourishingFluorine
Receptor Signaling and GPCRs Overview
78 questions

Receptor Signaling and GPCRs Overview

SumptuousSugilite7063 avatar
SumptuousSugilite7063
Lodish Ch 15: Signal Transduction I
35 questions

Lodish Ch 15: Signal Transduction I

TenaciousNephrite186 avatar
TenaciousNephrite186
Use Quizgecko on...
Browser
Open
Browser
Browser