BIOLOGY
5th Edition
ISBN: 9781265202859
Author: BROOKER
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Chapter 9.3, Problem 1CC
Summary Introduction
To explain: The beginning and end of the signal transduction pathway, and the cellular response in the given cell signaling pathway.
Introduction: GPCRs stand for G-protein-coupled-receptors. They are present in the cells of eukaryotes. G protein contains α subunits, and this subunit binds with adenylyl cyclase and triggers the synthesis of cyclic adenosine monophosphate (cyclic AMP).
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The G protein coupled receptor (GPCR) pathway elicits diverse intracellular responses in different cells. The basic steps of GPCR signaling are outlined in this diagram.
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Epinephrine
Plasma
Membrane
Beta-2
Adrenergic
Receptor
(GDP
(GDP G Protein
GTP
GTP
Adenylyl
Cyclase
O It breaks down glycogen
O it inhibits the glycolysis process
it binds to adenylyl cyclase
It phosphorylates phosphorylase kinase
It is inhibited by Cyclic AMP
ATP
Cyclic AMP
Protein Kinase A
-ATP
ADP
Phosphorylase Kinase
-ATP
ADP
Glycogen Phosphorylase
Glycogen
Glucose-1-Phosphate
Figure 1. A simplified model of the epinephrine signaling pathway in muscle cells
Which is true of Protein Kinase A?
Glycolysis
Chapter 9 Solutions
BIOLOGY
Ch. 9.1 - Figure 9.1 Response of a yeast cell to glucose....Ch. 9.1 - Prob. 1CSCh. 9.1 - Which type of signal, paracrine or endocrine, is...Ch. 9.1 - Prob. 3CCCh. 9.2 - Prob. 1CSCh. 9.2 - Prob. 2CSCh. 9.2 - Prob. 1CCCh. 9.3 - Prob. 1CSCh. 9.3 - Prob. 1CCCh. 9.3 - Prob. 2CC
Ch. 9.3 - In the case of signaling pathways involving...Ch. 9.5 - Prob. 1EQCh. 9.5 - Prob. 2EQCh. 9.5 - Prob. 3EQCh. 9.5 - Prob. 1CCCh. 9 - Prob. 1TYCh. 9 - Prob. 2TYCh. 9 - Prob. 3TYCh. 9 - Prob. 4TYCh. 9 - Prob. 5TYCh. 9 - The relay protein Ras is part of the EGF pathway...Ch. 9 - Prob. 7TYCh. 9 - Prob. 8TYCh. 9 - Prob. 9TYCh. 9 - Prob. 10TYCh. 9 - Prob. 1CQCh. 9 - Conceptual Questions What are the three stages of...Ch. 9 - Prob. 3CQCh. 9 - Prob. 1COQCh. 9 - Prob. 2COQ
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- You are studying a drug that affects a cAMP signalling pathway that is normally initiated when a signalling molecule binds to a G-protein coupled receptor. You determine that the drug prevents the hydrolysis of GTP bound to G-proteins in this pathway. Describe the impact, if any, that this drug would have on the G-protein coupled receptor (GPCR), assuming that the pathway has been activated by the presence of the signalling molecule (first messenger). Include an explanation for your response.arrow_forwardThe Luteinizing hormone receptor (LHR) is a GPCR that predominantly couples to Gαs (G alpha s) G proteins in response to binding of the endogenous ligand luteinizing hormone (LH). Briefly describe how activation of this receptor ultimately leads to protein kinase A (PKA) activation.arrow_forwardIn early studies of adrenergic signaling, it was thought that the epinephrine receptor and adenylate cyclase were one and the same protein. What kind of evidence would prove otherwise?arrow_forward
- In the case of GPCR (G protein coupled receptor) signaling pathways, which of the following statements is INCORRECT? The gamma subunit of the trimeric G protein has a transmembrane domain whereas the alpha and beta subunits are peripheral proteins If G alpha was locked in a GTP bound state, it would be bound to the effector enzyme rather than to the beta and gamma subunits. In some but not all signaling pathways, when the beta and gamma subunits are separated from alpha - the beta/gamma pair can also stimulate the activation of effectorsarrow_forwardA particular protein can bind to receptor tyrosine kinase molecules inhibiting their dimerization (stops them from being able to form dimers). Explain what effect you think this protein could have on the signal transduction pathways that use tyrosine kinase as a receptor if it were to be present in a cell.arrow_forwardWhat are the three main parts of a signaling pathway? Give a detailed specific example, such as how epinephrine signals for rapid digestion of glycogen in liver cells.arrow_forward
- Nerve-growth factor (NGF) binds to a protein tyrosine kinase receptor. The amount of diacylglycerol in the plasma membrane increases in cells expressing this receptor when treated with NGF. Propose a simple signaling pathway and identify the isoform of any participating enzymes. Would you expect the concentrations of any other common second messengers to increase on NGF treatment?arrow_forwardwhen kidney cells secrete low levels of oxygen in the blood they secrete erythropoietin. in this particular signaling pathway (response to low oxygen) the secretion of erythropoietin represents which step of the signal transdution process?arrow_forwardContinuous exposure of a Gαs protein coupled receptor to its ligand leads to a phenomenon known as desensitization. Describe several molecular mechanisms for receptor desensitization. How can a receptor be reset to its original sensitized state? What effect would a mutant receptor lacking serine or threonine phosphorylation sites have on a cell?arrow_forward
- List three ways in which a signal is amplified in a Gprotein-coupled receptor signaling pathway.arrow_forwardIdentify which of the following statements is a lie? Select one: a.Diacylglycerol (DAG) and inositol triphosphate (IP3) are byproducts of enzymatic cleaving of PIP2 using phospholipase C while PIP2 formed via enzymatic activity of kinases. b.cAMP is an important second messenger because it serves to activate or inactivate proteins within the cells, especially those cells which their metabolic pathways are regulated by cAMP-dependent kinase (A-kinase). c.Second messengers are molecules that act alternative to signaling molecules to bind to the receptors by altering the structure of cellular proteins.arrow_forwardSuppose that a G protein undergoes a mutation that allows the exchange of bound GTP for GDP to occur in the absence of G protein binding to a receptor. How might this mutation affect signaling involving a GPCR? Which subunit of the G protein is most likely affected by the mutation?arrow_forward
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