40 Questions
Which type of receptor does not use a secondary messenger?
Receptor tyrosine kinase (RTK)
What is the function of Grb2 and Sos adaptor proteins?
To bind to the receptor tyrosine kinase
What is the consequence of adrenaline binding to the α1-adrenergic receptor?
Inhibition of the EGF signalling pathway
What is the role of Ras in the EGF signalling pathway?
To trigger a kinase cascade
What is an example of convergence in cell signalling?
Different signals triggering the same pathway
What is the role of MAPKK in the Ras-MAP kinase pathway?
To activate MAPK
What is the function of PKA in the adrenaline signalling pathway?
To inhibit the EGF signalling pathway
What is the consequence of EGF binding to the EGF receptor?
Autophosphorylation of tyrosine residues
What is the primary function of transmembrane receptors in signal transduction pathways?
To transmit signals from the extracellular environment to the nucleus
Which of the following is NOT an example of a second messenger?
Glucagon
What is the primary role of G proteins in signal transduction pathways?
To activate downstream kinases and trigger signalling cascades
Which of the following is an example of a metabolic process regulated via intracellular signalling?
Glucagon-stimulated glycogen breakdown
What is the primary role of phospholipase C in signal transduction pathways?
To hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP2) to generate IP3 and diacylglycerol
Which of the following is an example of a cellular response to an extracellular signal?
Histamine release from mast cells
What is the primary function of receptor tyrosine kinases (RTKs) in signal transduction pathways?
To phosphorylate and activate downstream targets
Which of the following is an example of an extracellular signal?
Glutamate
What is the result of the binding of a signal molecule to a β-adrenergic receptor?
The receptor undergoes a conformational change, allowing G-protein binding.
What is the function of the α subunit in the G-protein complex?
To bind to the effector enzyme and activate it.
What is the result of GTP hydrolysis to GDP in the G-protein complex?
The α subunit is inactivated and the complex re-associates.
What is the role of the G-protein in the β-adrenergic receptor signalling pathway?
To translate the signal from the receptor to the effector enzyme.
What is the result of the dissociation of the G-protein complex?
The α subunit is activated and free to bind to the effector enzyme.
What is the role of GDP in the G-protein complex?
To inactivate the G-protein complex.
Which of the following hormone types binds to a receptor in the cytosol and triggers a response inside the cell?
Steroid
What is the result of the binding of acetylcholine to nicotinic acetylcholine receptor?
Depolarisation of membrane due to flow of ions
What is the function of the DNA binding domain in steroid hormones?
To bind to specific DNA sequences
What is the consequence of the binding of steroid hormone to its receptor?
Conformational change that allows DNA binding
What is the role of G-protein-coupled receptors (GPCRs) in cell signalling?
To generate secondary messengers
What is the consequence of the activation of adenylyl cyclase by G-protein-coupled receptors (GPCRs)?
Generation of cAMP
What is the function of the hormone binding domain in steroid hormones?
To bind to the hormone
What is the consequence of the activation of phospholipase C by G-protein-coupled receptors (GPCRs)?
Generation of IP3 and DAG
What is the consequence of GTP hydrolysis in the G-protein coupled receptor signalling pathway?
Re-association of the G-protein complex and termination of signalling
What is the role of the regulatory subunit in the cAMP dependent protein kinase A (PKA) pathway?
Binding to cAMP
What is the consequence of phosphorylase kinase activation in the glycogen breakdown pathway?
Activation of glycogen phosphorylase
What is the role of phosphodiesterase in the cAMP signalling pathway?
Converting cAMP to AMP
What is the consequence of CREB phosphorylation in the cAMP signalling pathway?
Stimulation of gene transcription
What is the role of Gαq in the GPCR signalling pathway?
Activating phospholipase C
What is the role of IP3 in the GPCR signalling pathway?
Activating Ca2+ channels
What is the consequence of DAG and Ca2+ activation in the GPCR signalling pathway?
Activation of protein kinase C
What is the role of cAMP in the signal amplification pathway?
Activating PKA
What is the consequence of PKA activation in the signal amplification pathway?
Activation of phosphorylase kinase
Study Notes
Receptor Activation of Phospholipase C
- α1-adrenergic (adrenaline) receptor directly activates enzymatic kinase cascade without secondary messenger
- Binding of EGF triggers autophosphorylation of tyrosine residues in cytoplasmic domain of receptor (Receptor Tyrosine Kinase, RTK)
- Adaptor proteins containing phosphotyrosine binding domains (SH2 and PTB) bind to receptor
- Complex of Grb2, Sos, and receptor activates Ras, a monomeric G-protein
- Ras triggers a kinase cascade (Ras-MAP kinase pathway) that activates transcription factor
G-Protein Coupled Receptors (GPCR)
- Generate cAMP, leading to activation of PKA
- Generate IP3, DAG, and Ca2+, leading to activation of PKC
- α-subunit of G-protein interacts with effector enzymes
- G-proteins can trigger different pathways, causing convergence and cross-talk
Intracellular Signalling
- Cells respond to extracellular signals through G-protein coupled receptors (GPCR) and receptor tyrosine kinase (RTK)
- GPCR can trigger different pathways, leading to convergence and cross-talk
- Different signals can trigger different pathways, causing overlap and cross-talk
Teaching Objectives
- Describe different ways for cells to signal to each other
- Explain the term 'second messenger' and give examples
- Describe the importance of transmembrane receptors and their associated signalling pathways in controlling gene activity
- Give examples of the roles of G proteins, cAMP, phospholipase C, diacylglycerol, inositol triphosphate (IP3), and Receptor Tyrosine Kinase (RTK) in signal transduction pathways
- Outline a metabolic regulated via intracellular signalling
- Recognise that overlap of signalling pathways can occur
- Beware that intracellular signalling is important in the action of drugs
Cellular Responses
- Change metabolic activities
- Secrete and release molecules
- Changes in gene expression
- Sensory perception
This quiz covers the activation of phospholipase C and receptor tyrosine kinase, including the binding of EGF and autophosphorylation of tyrosine residues.
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