BIOLOGY (OER)
2nd Edition
ISBN: 2810023110482
Author: OpenStax
Publisher: MBS
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Textbook Question
Chapter 9, Problem 1VCQ
Figure 9.8 HER2 is a receptor tyrosine kinase. In 30 percent of human breast cancers, HER2 is permanently activated, resulting in unregulated cell division. Lapatinib, a drug used to treat breast cancer, inhibits HER2 receptor tyrosine kinase autophosphorylation (the process by which the receptor adds phosphates onto itself), thus reducing tumor growth by 50 percent. Besides autophosphorylation, which of the following steps would be inhibited by Lapatinib?
- Signaling molecule binding, dimerization, and the downstream cellular response.
Expert Solution & Answer
Summary Introduction
Introduction:
Enzyme-linked receptors are the cell-surface receptors with intracellular domains that are associated with an enzyme. They normally have large extracellular and intracellular domains. The family of human epidermal growth factors receptor (HER) including the HER1, HER2, HER3 and HER4 play a central role in the pathogenesis of many human cancer.
Answer to Problem 1VCQ
Correct answer:
The correct answer is option (c)The downstream cellular response.
Explanation of Solution
Explanation/justification for the correct answer:
Option (c)The downstream cellular response. HER2 receptor is a 1255 amino acid, transmembrane glycoprotein. It is located on the long arm of the human chromosome 17 and its expression causes uncontrolled cell growth. This receptor undergoes dimerization on binding of the signaling molecule to the extracellular domain. This results in the process of autophosphorylation of the tyrosine residues on the intracellular domain which initiates a downstream cellular response. Lapatinib is a drug which inhibits the autophosphorylation of the tyrosine residues, thus inhibiting the process of downstream cellular response. So, the correct answer is option (c).
Explanation for incorrect answer:
Option (a)Signaling molecule binding, dimerization, and the downstream cellular response. The binding of a signaling molecule to the extracellular domain of the receptor causes dimerization initiating a downstream cellular response. So, this is an incorrect option.
Option (b)Dimerization, and the downstream cellular response. The processes such as dimerization and the downstream cellular response are not inhibited due to the binding of a signaling molecule to its extracellular domain. So, this is an incorrect option.
Option (d) Phosphatase activity, dimerization, and the downstream cellular response. It also exhibits phosphatase activity causing the removal of phosphates and termination of the signal after dimerization and downstream cellular response. So, this is an incorrect option.
Conclusion
Thus, Lapatinib is a drug which inhibits the process of downstream cellular responseapart from autophosphorylation.Hence, the correct answer is option (c) The downstream cellular response.
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I just read an abstract of the paper “Disulfide bond-disrupting agents activate the tumor necrosis family-related apoptosis-inducing ligand/death receptor 5 pathway” and noted that “DDAs and TRAIL synergize to kill cancer cells and are cytotoxic to HER2+ cancer cells with acquired resistance to the EGFR/HER2 tyrosine kinase inhibitor Lapatinib.”
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Suppose that Protein J which is a hypothetical protein kinase receptor was determined to
be related to the progression of cancer through its activation. It was also determined that the
protein exists in the active and inactive forms. The said active form is highly similar to the Protein
K's conformation. Ligands A, B, and C, which are lead inhibitor compounds, were optimized to
inhibit Protein J. The affinities of the ligands are shown in the table.
Kp values
Active Protein J
Inactive Protein J
Protein K
Ligand A
10 mM
20 nM
5 mM
Ligand B
20 nM
10 mM
15 nM
Ligand C
20 nM
15 nM
15 nM
Question:
a. Which of the ligands, based on the table, has the highest specificity in binding to the
target Protein J?
Chapter 9 Solutions
BIOLOGY (OER)
Ch. 9 - Figure 9.8 HER2 is a receptor tyrosine kinase. In...Ch. 9 - Figure 9.10 In certain cancers, the GTPase...Ch. 9 - Figure 9.17 Which of the following statements...Ch. 9 - Figure 9.18 What advantage might biofilm...Ch. 9 - What property prevents the ligands of cell-surface...Ch. 9 - The secretion of hormones by the pituitary gland...Ch. 9 - Why are ion channels necessary to transport ions...Ch. 9 - Endocrine signals are transmitted more slowly than...Ch. 9 - A scientist notices that when she adds a small,...Ch. 9 - Where do DAG and IP3 originate? They are formed by...
Ch. 9 - What property enables the residues of the amino...Ch. 9 - Histamine binds to the H1 G-protein-linked...Ch. 9 - A scientist observes a mutation in the...Ch. 9 - What is the function of a phosphatase? A...Ch. 9 - How does NF-kB induce gene expression? A small,...Ch. 9 - Apoptosis can occur in a cell when the cell is...Ch. 9 - What is the effect of an inhibitor binding an...Ch. 9 - How does PKC’s signaling role change in response...Ch. 9 - A scientist notices that a cancer cell line fails...Ch. 9 - Which type of molecule acts as a signaling...Ch. 9 - Quorum sensing is triggered to begin when...Ch. 9 - A doctor is researching new ways to treat biofilms...Ch. 9 - What is the difference between intracellular...Ch. 9 - How are the effects of paracrine signaling limited...Ch. 9 - What are the differences between internal...Ch. 9 - Cells grown in the laboratory are mixed with a dye...Ch. 9 - Insulin is a hormone that regulates blood sugar by...Ch. 9 - The same second messengers are used in many...Ch. 9 - What would happen if the intracellular domain of a...Ch. 9 - If a cell developed a mutation in its MAP2K1 gene...Ch. 9 - What is a possible result of a mutation in a...Ch. 9 - How does the extracellular matrix control the...Ch. 9 - A scientist notices that a cancer cell line shows...Ch. 9 - What characteristics make yeasts a good model for...Ch. 9 - Why is signaling in multicellular organisms more...Ch. 9 - Pseudomonas infections are very common in hospital...
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