Concept explainers
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.
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.
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.
Want to see more full solutions like this?
Chapter 9 Solutions
Biology 2e
Additional Science Textbook Solutions
College Physics
Biological Science (6th Edition)
Campbell Essential Biology (6th Edition) - standalone book
Biology: Life on Earth (11th Edition)
Campbell Biology (11th Edition)
Campbell Biology: Concepts & Connections (9th Edition)
- What type of cell signaling receptor is depicted below a. Cytoplasmic Receptor b. Transmembrane Receptor c. Intracellular Receptor d. Nuclear Receptorarrow_forwardWhich of the following statements are correct about cytoplasmic signaling in cancer cells? Multiple answers. A. Only minor modifications of cell control machinery are required for normal cells to become highly proliferating cancer cells B. Immediate early genes are induced in the presence of protein synthesis inhibitors C. Many immediate -early genes are oncogenes D. Delayed early genes are highly expressed in the presence of protein synthesis inhibitors E. Delayed early genes are highly expressed in normal cells in the absence of growth factorsarrow_forwardTo move in a specific direction, a migrating cell must use extracellular cues to establish which portion of the cell will act as the front and which will act as the back. Describe how small GTPase proteins appear to be involved in the signaling pathways used by migrating cells to determine direction of movement.arrow_forward
- 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. Which of the following statements correctly describes the process of GPCR signaling? The GPCR activation is reversible after the signal of the ligand diminishes. The membrane-embedded enzyme uses GTP as a secondary messenger to initiate gene expression. The ligand attaches to both the GPCR and the membrane-embedded enzyme to activate the GPCR pathway. The ligand-bound GPCR sends a GTP molecule to an enzyme in the membrane and switches it into an active state.arrow_forwardIn a patient with a constitutively active receptor tyrosine kinase that increases the activity of PI3K, the administration of a drug that increases PTEN expression will likely inhibit tumorigenesis because; Group of answer choices PTEN prevents growth factor binding to RTK PTEN competitively inhibits the catalytic subunit of PI3K PTEN dephosphorylates PIP3 PTEN inhibits the dimerization of the regulatory subunit of RTKsarrow_forwardProtein phosphorylation is commonly involved with all of thefollowing except(A) activation of receptor tyrosine kinases.(B) activation of protein kinase molecules.(C) activation of G protein-coupled receptors.(D) regulation of transcription by signaling molecules.arrow_forward
- Cholera toxins, produced by the pathogenic bacteria Vibrio cholerae, disrupt G Protein Coupled Receptor (GPCR) signaling pathways. They interfere with... the ability of the beta subunit of a G protein to bind to the GPCR the ability of the gamma subunit of a G protein to exchange GDP for GTP the ability of the beta subunit of a G protein to bind to an effector protein the ability of the alpha subunit of a G protein to hydrolyze GTP to GDParrow_forwardWhich of the following would be expected to inhibit PKC activation by a GPCR ligand? phospholipase C inhibitor cAMP phosphodiesterase inhibitor Ras inhibitor MAP kinase inhibitorarrow_forwardWhen epidermal growth factor (EGF)—the ligand for the epidermal growth factor receptor (EGFR)—binds EGFR on the cell surface, the intracellular domain of the receptor changes shape into an "active state.” The receptor then induces a cascade of kinases in the cytoplasm, resulting in the activation of mitogen-activated protein kinase (MAPK). One effect of EGFR signaling is the stimulation of cell proliferation. Overactive EGFR is frequently found in cancer cells. One strategy for developing anticancer drugs is to target the overactive signaling proteins found in cancer cells. Antibodies are proteins made by immune cells that only recognize specific biomolecules, called antigens. The major component of an anticancer drug is an antibody that specifically recognizes and binds EGFR. Which of the following will most likely happen when this anticancer drug is applied to a tumor that has a high level of EGFR? Tumor cells with active EGFR will increase and MAPK activity in the tumor will…arrow_forward
- which of hthe following would result in a persisting proliferation response to growth factor receptor activation after the ligand is no longer binding to its rceptor kinase? 1. Both a mutation that blocks the GTPas activity of Ras and a mutation that blocks the exchange of GDP with GTP would cause the response to persist. 2. a mutation that blocks the GTPas activity of Ras 3. neither a mutation that blocks the GTPas activity of Ras nor a mutation that blocks the exchange of GDP with GTP would cause the response to persist 4. a mutatiaon that blocks the exchange of GDP with GTParrow_forwardwhich of the following correctly describes how protein kinase A can activate genes? A: nuclear protein kinase A is activated by cAMP to phosphorylate general transcription factors B: cytosolic protein kinase A is activated by cAMP to release the catalytic subunits, which move into the nucleus and phosphorylate CREB C: cytosolic protein kinase A is activated by cAMP to release the catalytic subunits, which move into the nucleus and phosphorylate general transcription factors D: G protein-coupled receptors may be desensitized by serine phosphorylationarrow_forwardA tumor cannot grow to be very large without the development of new blood vessels (angiogenesis) to provide access to oxygen and nutrients. During the 1990s, it was discovered that Factor X stimulates the proliferation and migration of the cells that form blood vessels, thereby inducing the formation of new blood vessels. Factor X binds to specific receptor tyrosine kinases (RTKs) on the cell surface and causes the RTKs to dimerize and become active, initiating an intracellular signaling cascade that stimulates cell division and inhibits apoptosis. Many cancer cells secrete high levels of Factor X, and increased Factor X expression in a tumor is correlated with a poor medical outcome for the patient. Some evidence suggests that blocking Factor X-dependent signaling may prevent the formation of new blood vessels and lead to the death of immature blood vessels without disturbing mature blood vessels. You work for a biotechnology company that seeks to create anticancer drugs that…arrow_forward
- Biology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStax