Upon activation by a receptor, a G protein exchanges bound GDP forGTP, rather than phosphorylating GDP that is already bound. Similarly,the a subunit-GTP complex has a slow GTPase activity that hydrolyzesbound GTP, rather than exchanging it for GDP. Describe experimentalevidence that would be consistent with these conclusions.

The G-protein is heterotrimeric. It has alpha, beta, and gamma subunits. When GDP is bound to the…

Answered: Upon activation by a receptor, a G…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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Similar questions

Ligand binding to proteins may occur with varying strengths; some ligands bind tightly to proteins while others bind less tightly. The strengths of reversible binding are determined experimentally by varying concentrations of ligands, and measuring the saturation of the protein in the various ligand concentrations. One such laboratory study investigated the binding of a hormone to three different receptor proteins in the cell membrane. The data collected are shown in the table below: 1) Provide a brief explanation as to why ligand binding to proteins must be a reversible process. 2) Calculate the dissociation constant (Kd) for the hormone binding to each of the three proteins.
Explain , What role does phosphorylation of tyrosine residues play in the action of receptor proteins?
You decide to investigate cell signaling of a pair of newly identified GPCRs, GPCR-W and GPCR-Z. Each binds the same ligand, but activates different downstream heterotrimeric G-proteins that act on adenylyl cyclase. You discover that ligand binding has opposite effects on adenylyl cyclase activity for each receptor. GPCR-W causes an increase in adenylyl cyclase activity, while GPCR-Z causes a decrease in adenylyl cyclase activity. You obtain a cell line expressing GPCR-W, GPCR-Z, the relevant G-proteins, and adenylyl cyclase. There is baseline adenylyl cyclase activity producing a baseline amount of cAMP. You embark on a research project to characterize the following mutations in the components of the signaling pathway. 2. Will each of the following mutations increase or decrease the levels of cAMP inside the cell upon adding the ligand to the cell culture? A mutation in Gi that prevents release of bound GDP. A mutation in Gs that prevents GTP hydrolysis. A mutation in Gi that…
What do the cytoplasmic domain of a G protein-coupled receptor and the adaptor protein in the RTK pathway have in common?
A signaling molecule M is active when it is phosphorylated (M-P). The M-P has downstream target molecules in nucleus. Provide a possible mechanism by which M does its job
Phosphatidylethanolamine and PIP2 containing identical fatty acyl residues can be hydrolyzed with the same efficiency by a certain phospholipase C. Will the hydrolysis products of the two lipids have the same effect on protein kinase C? Explain.
Steroid hormones are required by the body at puberty and into adolescence to regulate growth and cell division at more rapid pace than in later life. This regulation occurs via their interaction with cellular receptors and the signaling cascades/pathways that follow. Describe for me the difference between the two major classes of steroids, anabolic and catabolic steroids. What might you expect the result of signaling cascades to be in cells receiving either anabolic or catabolic “signals”? (B) At some point in late adolescence, steroid production decreases by almost 100 fold, as we transition into “adulthood”. Why might we wish to stop these signals from constantly being in our blood stream, (like, Say, between 17-24 years of age)? What result might these steroids have on cancer cells where abhorrent signaling is already causing an increased rate of cell division/growth? Could steroid use result in Cancer?
Binding EGF to the EGF receptor causes phosphorylation of tyrosines on the cytoplasmic tail of the receptor. Which of the following best describes the mechanism by which this phosphorylation activates downstream signaling complexes? Select one A. Causes degradation of receptor by proteasome pathway B. Causes EGF receptor to be internalized so it can interact directly with downstream signaling molecules C. Tyrosine phosphorylation alters 3D structure of downstream signaling proteins causing them to change from an inactive to active conformation D. Causes release of EGF from receptor E. Alters the localization of downstream signaling partners in the cytoplasm
For the protein Calmodulin-1: 1) this protein have any secondary, tertiary and/or quaternary structures present? 2) Are there any molecular additions to this protein that are not amino acids?For both questions, can you explain if so, where specifically? The protein Calmodulin-1 is stated to have the molecular function of signaling receptor binding which is interrelated with the biological function of calcium-mediated signaling. Can you explain this relationship?
Does adenylate cyclase become more active when the inhibitory (Gia) protein is mutated and increases its intrinsic GTPase activity?
Would nitrosylation of cysteine or ubiquitination of lysine disrupt binding the most in a G protein coupled receptor?
Explain how a tyrosine kinase (YK) receptor becomes phosphorylated and activated upon ligand binding.

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