Signal Amplification in Signaling Pathways

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Which term describes the phenomenon where the number of activated participants in a signal transduction pathway increases at each step?

Signal amplification (correct)

GTPase activation

Amplification switch

Phosphorylation cascade

What type of proteins play important roles in intracellular signal transduction by being active when bound to GTP and inactive when bound to GDP?

Kinases

Adenylyl cyclases

Hormone receptors

GTPase switch proteins (correct)

Which proteins promote the exchange of GTP for GDP and activate GTPases?

Kinases

GTPase-activating proteins (GAPs)

Adenylyl cyclases

Guanine nucleotide-exchange factors (GEFs) (correct)

What do kinases use to phosphorylate amino acid sidechains in target proteins?

ATP Signup and view all the answers

Which type of proteins stimulate the rate of GTP hydrolysis to GDP and inactivate GTPases?

GTPase-activating proteins (GAPs) Signup and view all the answers

What is estimated to be the overall amplification associated with epinephrine signaling?

~100-fold Signup and view all the answers

Which type of signaling pathways are often referred to as amplification cascades?

Hormone signaling pathways Signup and view all the answers

What is the function of hormone-activated GPCRs in epinephrine signaling?

Activate many adenylyl cyclases Signup and view all the answers

What is the role of an orthosteric ligand in GPCR signaling?

It binds to an inactive GPCR to activate it Signup and view all the answers

How many distinct GPCRs have had their crystal structures solved so far?

44 Signup and view all the answers

Which subfamily do all the four classes A–C, and F belong to?

Class A Signup and view all the answers

What is the primary outcome of binding of a ligand to a GPCR?

Activation of downstream effectors Signup and view all the answers

In GPCR signaling, what happens when a GPCR binds a G protein?

The α chain dissociates from the b g complex and binds to its effector molecule Signup and view all the answers

What does IC PAM refer to in the context of GPCR crystal structures?

Binding of a ligand to an inhibitor Signup and view all the answers

What is the function of a GPCR as a GEF?

Allows binding of G protein by changing the conformation of the receptor Signup and view all the answers

What is the main outcome of ligand binding in G-protein receptor activation?

Switching the α subunit to its activated state Signup and view all the answers

What is the primary role of bound GTP in G-protein receptor activation?

Dissociation from the bg complex and binding to its effector molecule Signup and view all the answers

Which type of GPCR has seven transmembrane helices?

Class A/Rhodopsin family GPCRs Signup and view all the answers

What type of ligands are shown as purple sticks in the representative structures?

Agonists Signup and view all the answers

What do the prenyl groups -3-methylbut-2-en-1-yl represent in the context of GPCR?

GPCR subunits Signup and view all the answers

In which class of nonrhodopsin GPCRs is the representative structure A2A AR found?

Nucleotide-like Signup and view all the answers

What differentiates class A/Rhodopsin family GPCRs from other classes?

Presence of seven transmembrane helices Signup and view all the answers

What is the role of helix VIII in GPCRs?

Runs parallel to the membrane near the C-terminus Signup and view all the answers

Which class of nonrhodopsin GPCR does the representative structure SMO belong to?

Class F GPCRs Signup and view all the answers

What type of ligands are shown as blue stick models in the representative structures?

Negative allosteric modulators Signup and view all the answers

What is the composition of class B GPCRs?

CRF1, GCGR, GLP-1R, CTR Signup and view all the answers

What is the overall amplification associated with epinephrine signaling estimated to be?

~10^8-fold Signup and view all the answers

What is the primary role of guanine nucleotide-exchange factors (GEFs) in intracellular signal transduction?

Promote exchange of GTP for GDP and activate GTPases Signup and view all the answers

Which proteins play important roles in intracellular signal transduction by being active when bound to GTP and inactive when bound to GDP?

GTPase switch proteins Signup and view all the answers

What is the function of GTPase-activating proteins (GAPs) in the regulation of signaling ON/OFF?

Stimulate the rate of GTP hydrolysis to GDP and inactivate GTPases Signup and view all the answers

Which proteins use ATP to phosphorylate amino acid sidechains in target proteins?

Kinases Signup and view all the answers

Which type of G-protein coupled receptor (GPCR) family consists of hundreds of receptors and has a 7-transmembrane (7TM) structure in the membrane?

Class A/Rhodopsin family Signup and view all the answers

Which type of ligand is represented by purple sticks in the representative structures of GPCRs?

Agonists Signup and view all the answers

What is the role of helix VIII in GPCRs?

It is located near the crystallization techniques Signup and view all the answers

In GPCR signaling, what happens when a GPCR binds a G protein?

The G protein releases GDP and binds to GTP Signup and view all the answers

What do the prenyl groups -3-methylbut-2-en-1-yl represent in the context of GPCR?

They form part of the γ subunit prenylation Signup and view all the answers

What is the primary outcome of binding of a ligand to a GPCR?

Conformational change in the receptor Signup and view all the answers

Which class of nonrhodopsin GPCR does the representative structure SMO belong to?

Class F Signup and view all the answers

In which part of the cell membrane are nonrhodopsin GPCRs typically located?

Transmembrane helices Signup and view all the answers

What is the primary challenge in elucidating GPCR structures?

Allosteric binding sites Signup and view all the answers

In Class A GPCRs, what structural change occurs when a ligand binds?

TM2 rotates and swings away Signup and view all the answers

What kind of conformations are shown in Figure 6 representing structural rearrangements during GPCR activation?

Inactive and active conformations Signup and view all the answers

What are the distinct regions of the GPCR highlighted in Figure 6 for differences in helix position and side-chain orientation?

The binding pocket and the intracellular coupling site Signup and view all the answers

What characterizes the transmembrane domain of the GPCR?

Membrane helices and three extracellular loops Signup and view all the answers

What does TM6 do when a ligand binds in Class A receptors?

Rotates and swings away from the center Signup and view all the answers

Signal Amplification in Signaling Pathways

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Questions and Answers

Which term describes the phenomenon where the number of activated participants in a signal transduction pathway increases at each step?

What type of proteins play important roles in intracellular signal transduction by being active when bound to GTP and inactive when bound to GDP?

Which proteins promote the exchange of GTP for GDP and activate GTPases?

What do kinases use to phosphorylate amino acid sidechains in target proteins?

Which type of proteins stimulate the rate of GTP hydrolysis to GDP and inactivate GTPases?

What is estimated to be the overall amplification associated with epinephrine signaling?

Which type of signaling pathways are often referred to as amplification cascades?

What is the function of hormone-activated GPCRs in epinephrine signaling?

What is the role of an orthosteric ligand in GPCR signaling?

How many distinct GPCRs have had their crystal structures solved so far?

Which subfamily do all the four classes A–C, and F belong to?

What is the primary outcome of binding of a ligand to a GPCR?

In GPCR signaling, what happens when a GPCR binds a G protein?

What does IC PAM refer to in the context of GPCR crystal structures?

What is the function of a GPCR as a GEF?

What is the main outcome of ligand binding in G-protein receptor activation?

What is the primary role of bound GTP in G-protein receptor activation?

Which type of GPCR has seven transmembrane helices?

What type of ligands are shown as purple sticks in the representative structures?

What do the prenyl groups -3-methylbut-2-en-1-yl represent in the context of GPCR?

In which class of nonrhodopsin GPCRs is the representative structure A2A AR found?

What differentiates class A/Rhodopsin family GPCRs from other classes?

What is the role of helix VIII in GPCRs?

Which class of nonrhodopsin GPCR does the representative structure SMO belong to?

What type of ligands are shown as blue stick models in the representative structures?

What is the composition of class B GPCRs?

What is the overall amplification associated with epinephrine signaling estimated to be?

What is the primary role of guanine nucleotide-exchange factors (GEFs) in intracellular signal transduction?

Which proteins play important roles in intracellular signal transduction by being active when bound to GTP and inactive when bound to GDP?

What is the function of GTPase-activating proteins (GAPs) in the regulation of signaling ON/OFF?

Which proteins use ATP to phosphorylate amino acid sidechains in target proteins?

Which type of G-protein coupled receptor (GPCR) family consists of hundreds of receptors and has a 7-transmembrane (7TM) structure in the membrane?

Which type of ligand is represented by purple sticks in the representative structures of GPCRs?

What is the role of helix VIII in GPCRs?

In GPCR signaling, what happens when a GPCR binds a G protein?

What do the prenyl groups -3-methylbut-2-en-1-yl represent in the context of GPCR?

What is the primary outcome of binding of a ligand to a GPCR?

Which class of nonrhodopsin GPCR does the representative structure SMO belong to?

In which part of the cell membrane are nonrhodopsin GPCRs typically located?

What is the primary challenge in elucidating GPCR structures?

In Class A GPCRs, what structural change occurs when a ligand binds?

What kind of conformations are shown in Figure 6 representing structural rearrangements during GPCR activation?

What are the distinct regions of the GPCR highlighted in Figure 6 for differences in helix position and side-chain orientation?

What characterizes the transmembrane domain of the GPCR?

What does TM6 do when a ligand binds in Class A receptors?

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