Lodish Ch 16: Signaling Pathways and Gene Activity Overview

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Questions and Answers

Latent TGF is converted to mature TGF by:

Dephosphorylation

Phosphorylation

Proteolysis (correct)

Translocation

None of the above

A loss-of-function mutation in which of the following would inhibit TGF signaling?

I-Smad

R-Smad (correct)

Ski

SnoN

All of the above

A gain-of-function mutation in which of the following would promote malignancy in cells whose proliferation is inhibited by TGF?

Co-Smad

I-Smad (correct)

R-Smad

All of the above

None of the above

Which of the following receptors binds TGF?

Type III Signup and view all the answers

TGF-β normally promotes:

Tissue organization Signup and view all the answers

Which of the following contain(s) an SH2 domain?

All of the above Signup and view all the answers

Binding of erythropoietin to its extracellular receptor engages which of the following signaling pathways?

All of the above Signup and view all the answers

Which of the following mechanisms is NOT used to terminate cytokine signaling and the JAK/STAT pathway?

Heterodimerization of cytokine receptors Signup and view all the answers

The EGF receptor is a(n):

Kinase Signup and view all the answers

Binding of hormone to a receptor tyrosine kinase causes all of the following, except:

Hydrolysis of GTP bound to Ras Signup and view all the answers

Which of the following is a protein kinase?

EGF receptor Signup and view all the answers

Ras is a(n):

None of the above Signup and view all the answers

In which of the following double-mutant flies will R7 photoreceptors develop normally?

Constitutively active MAPK and inactive Ras Signup and view all the answers

Serum response factor (SRF) is phosphorylated by:

p90 RSK Signup and view all the answers

Transcriptional activation downstream of the MAPK pathway involves:

Binding of transcription factors to the SRE of c-Fos Signup and view all the answers

Before ligand binding, receptor tyrosine kinases:

Contain activation lip tyrosines within the kinase active site Signup and view all the answers

Many PTB-containing proteins act as docking sites for multiple proteins. If these proteins are involved in the RTK signal transduction pathway, they most likely:

Are adopting a different conformation (shape) to expand the pathways affected by ligand binding Signup and view all the answers

An SH2-containing protein contains a mutation that changes its binding pocket such that tyrosine and phosphotyrosine bind with equal affinity. As a result, MEK activity:

Does not change with receptor dimerization and transautophosphorylation Signup and view all the answers

Which of the following is NOT true about the role of adapter proteins in the activation of Ras by receptor tyrosine kinases?

Sos acts as a GAP, which helps convert Ras GDP to active Ras-GTP Signup and view all the answers

The order of events in a signaling pathway can be determined by the analysis of mutants. Cells that express a mutant defective Raf protein cannot be stimulated to proliferate uncontrollably by constitutively active Ras (dominant active). This indicates:

Ras is upstream of Raf in the signaling pathway. Signup and view all the answers

How can multiple MAP kinase pathways be segregated when they share a common component, like a downstream kinase?

Formation of pathway-specific complexes assembled on molecular scaffolds Signup and view all the answers

Which of the following explains why Ras is activated quickly by RTKs?

Ras is maintained at the plasma membrane through a lipid-mediated attachment Signup and view all the answers

Which protein stabilizes an intermediate in the Ras GTP hydrolysis reactions?

Sos Signup and view all the answers

By what mechanism does PI-3 phosphate promote activation of protein kinase B (PKB)?

All of the above Signup and view all the answers

Which of the following are enzyme pairs that catalyze opposite reactions?

PI-3 kinase and PTEN phosphatase Signup and view all the answers

Which of the following signaling pathways can be activated by cytokines?

All of the above Signup and view all the answers

All genes regulated by PKA contain a cis-acting DNA sequence that binds to the phosphorylated form of a transcription factor called:

CREB Signup and view all the answers

Predict the consequences of a temperature-sensitive mutation in which phosphorylation of the β-catenin protein is blocked. Above the permissive temperature:

β-catenin levels will increase and β-catenin will be constitutively active Signup and view all the answers

In the NF-κB signaling pathway, which of the following molecules is downstream of IκB kinase?

NF-κB Signup and view all the answers

Which of the following is cleaved by regulated intramembrane proteolysis (RIP)?

Notch Signup and view all the answers

NF-κB signaling is important in:

Inflammation Signup and view all the answers

Study Notes

Signaling Pathways That Control Gene Activity

Latent TGF is converted to mature TGF through proteolysis.
A loss-of-function mutation in R-Smad inhibits TGF signaling.
A gain-of-function mutation in I-Smad promotes malignancy in cells whose proliferation is inhibited by TGF.
TGF binds to both type II and type III receptors.
TGF signaling molecules are secreted and stored in the extracellular matrix, in an inactive form. They can be activated by proteolytic digestion when needed.
Ski and SnoN inhibit TGF signaling by binding to nuclear Smad complexes, preventing modulation of gene expression. Constitutive expression promotes cancer by preventing TGF from controlling cell division.
TGF normally promotes tissue organization.
SHP1 and SOCS proteins down-regulate erythropoietin signaling by different mechanisms.
- SHP1 is a phosphatase that inhibits JAKs.
- SOCS proteins inhibit JAKs and recruit ubiquitin ligases to degrade them.
Receptor tyrosine kinases (RTKs) are often subjected to receptor-mediated endocytosis after ligand binding. This downregulates the signal.
Transcriptional activation downstream of MAPK pathway involves CREB phosphorylation and binding of transcription factors to the SRE of c-Fos.
Ras is activated when Sos binds and catalyzes the exchange of GDP for GTP resulting in an active Ras protein, and is deactivated by a guanine nucleotide exchange factor (GEF).
Ras is converted to inactive form by the action of GEF and GAP (guanine nucleotide exchange factor and GTPase-activating protein) causing conversion to inactive Ras GDP.
Multiple MAP kinase pathways are segregated by pathway-specific complexes assembled on molecular scaffolds.
Serum response factor (SRF) is phosphorylated by p90RSK.
R7 photoreceptors develop normally with constitutively active MAPK and inactive Ras.
PI-3 phosphate promotes activation of protein kinase B (PKB) by recruiting PKB and PDK1 to the plasma membrane.
MEK and MAP kinase catalyze opposite reactions.
NF-κB activation is downstream of IκB kinase.
Ligand Delta of transmembrane receptors is unlike other ligands(EGF, TGF, erythropoietin) because Delta stays in place(is not diffusible).

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Description

Explore the intricate signaling pathways that regulate gene activity, focusing on TGF signaling and its impact on cell proliferation and malignancy. This quiz covers key mechanisms, including the roles of R-Smad and I-Smad in TGF signaling and the involvement of SHP1 and SOCS proteins in erythropoietin signaling. Delve into the molecular interactions that play crucial roles in tissue organization and cancer development.

Lodish Ch 16: Signaling Pathways and Gene Activity Overview

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Podcast

Questions and Answers

Latent TGF is converted to mature TGF by:

A loss-of-function mutation in which of the following would inhibit TGF signaling?

A gain-of-function mutation in which of the following would promote malignancy in cells whose proliferation is inhibited by TGF?

Which of the following receptors binds TGF?

TGF-β normally promotes:

Which of the following contain(s) an SH2 domain?

Binding of erythropoietin to its extracellular receptor engages which of the following signaling pathways?

Which of the following mechanisms is NOT used to terminate cytokine signaling and the JAK/STAT pathway?

The EGF receptor is a(n):

Binding of hormone to a receptor tyrosine kinase causes all of the following, except:

Which of the following is a protein kinase?

Ras is a(n):

In which of the following double-mutant flies will R7 photoreceptors develop normally?

Serum response factor (SRF) is phosphorylated by:

Transcriptional activation downstream of the MAPK pathway involves:

Before ligand binding, receptor tyrosine kinases:

Many PTB-containing proteins act as docking sites for multiple proteins. If these proteins are involved in the RTK signal transduction pathway, they most likely:

An SH2-containing protein contains a mutation that changes its binding pocket such that tyrosine and phosphotyrosine bind with equal affinity. As a result, MEK activity:

Which of the following is NOT true about the role of adapter proteins in the activation of Ras by receptor tyrosine kinases?

The order of events in a signaling pathway can be determined by the analysis of mutants. Cells that express a mutant defective Raf protein cannot be stimulated to proliferate uncontrollably by constitutively active Ras (dominant active). This indicates:

How can multiple MAP kinase pathways be segregated when they share a common component, like a downstream kinase?

Which of the following explains why Ras is activated quickly by RTKs?

Which protein stabilizes an intermediate in the Ras GTP hydrolysis reactions?

By what mechanism does PI-3 phosphate promote activation of protein kinase B (PKB)?

Which of the following are enzyme pairs that catalyze opposite reactions?

Which of the following signaling pathways can be activated by cytokines?

All genes regulated by PKA contain a cis-acting DNA sequence that binds to the phosphorylated form of a transcription factor called:

Predict the consequences of a temperature-sensitive mutation in which phosphorylation of the β-catenin protein is blocked. Above the permissive temperature:

In the NF-κB signaling pathway, which of the following molecules is downstream of IκB kinase?

Which of the following is cleaved by regulated intramembrane proteolysis (RIP)?

NF-κB signaling is important in:

Study Notes

Signaling Pathways That Control Gene Activity

Studying That Suits You

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