A mutated form of the a subunit of the heterotrimeric G protein has been identified. It isfound to readily exchange GDP for GTP even the absence of an activated receptor.a. What would be the effect on a signaling pathway containing the mutated protein? And in light ofyour answer would this protein more likely to function as an oncogene or as a tumor suppressor.Briefly explain your answer.b. A paper finds an interesting study where an analog of GTP (GTPYS,guanosine 5'-0-[gamma-thio]triphosphate) is used to alter G-proteinactivity. The authors claim that the data below suggest that it couldperhaps be used as a treatment for patients with the mutated a subunitas described above. What do you think?HO[P]OH OH ONOH OHGTPYSRate of HydrolysisTimeGTPI GTPYS

Heterotrimeric G proteins have 3 subunits; , and . GPCRs (G protein coupled receptors) are…

Answered: A mutated form of the a subunit of the…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter32: The Reception And Transmission Of Extracellular Information

Section: Chapter Questions

Problem 21P

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Cancer-promoting mutations are likely to have different effects on the activity of proteins encoded byproto-oncogenes than they do on proteins encodedby tumor-suppressor genes. Explain.
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?
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: Describe the relative binding affinities of Ligand A to Protein K and to the active and inactive forms of Protein J. Determine which will Ligand A bind with the highest, medium, and lowest affinity.
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, may be expected to be the most potent or have the highest activity against cancer? Explain. b. Which of the ligands, based on the table, may be expected to be least toxic to normal cells? Explain.
When Hedgehog binds to Patched, this not only activates the signaling pathway but alsoactivates the receptor-mediated endocytosis of Patched, so there is less Patched on the plasmamembrane to inhibit Smoothened. a. Outline the steps of receptor-mediated endocytosis, including the roles for each proteininvolved. Hint: if your answer does not include the protein dynamin, you are notproviding enough detail. b. What will happen to Patched after it enters the cell via receptor-mediated endocytosis?Assume that Patched is not recycled back to the plasma membrane.
RTKs are receptors made of an extracellular ligand binding domain and an intracellular kinase domain (see image). Insulin binds to its RTK Insulin receptor, causing an increase in glucose absorption and storage in liver cells. EGF binds to its own RTK, EGFR and promotes cell growth through the Ras pathway. a) Explain why the same type of tyrosine kinase in two RTKs can lead to very different cellular responses. Give an example of potential cellular outputs for each of these two RTKs.
Signaling pathways often require receptor dimers to become active. What would be an advantage of the extrinsic apoptosis pathway requiring a trimer? I note from the article "Nature Reviews, Cancer 16:539, 2016" the following: The extrinsic apoptotic pathway, upon binding to their cognate ligand, death receptors such as tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptor (TRAILR) and FAS can activate initiator caspases (caspase-8 and caspase-10) through dimerization mediated by adaptor proteins such as FAS-associated death domain protein (FADD). Active caspase-8 and caspase-10 then cleave and activate the effector caspase-3 and caspase-7, leading to apoptosis. I can't think of any other pathway that uses a trimer, so there must be a reason. Glad an exprt can help.
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.” For the last sentence, I am not sure the meaning of the “acquired resistance to the EGFR/HER2 tyrosine kinase inhibitor Lapatinib”. Is the “acquired resistance ... to inhibitor” a good thing or bad thing, as far as the synergize effect of DDAs and TRAIL”? Hope that expert can help.
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To understand how a signaling pathway works, it is often useful to isolate the cell-surface receptor and to measure the activity of downstream effector proteins under different conditions. How could you use affinity chromatography to isolate a cell-surface receptor?
A current focus of molecular medicine is to trigger or promote apoptosis of specific cells. several components of the apoptotic pathways are being targeted using this approach. for each of the following, state specifically how the treatment would be expected to stimulate or inhbit apoptosis. b. exposing cells to recombinant TRAIL protein, a ligand for thr tumor necrosis factor family of receptors
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