An important aspect of phosphor-peptide recognition by SH2 domains is an invariant aspartate side chain that has favorable interactions with the negatively charged phosphate group on the peptide. TRUE FALSE When considering the mechanism of protein-ligand binding, the concept of conformational capture suggests that the conformation of the protein required for ligand binding exists as one of many nearly isoenergetic conformational states. TRUE FALSE

An important aspect of phosphor-peptide recognition by SH2 domains is an invariant aspartate side chain that has favorable interactions with the negatively charged phosphate group on the peptide. TRUE FALSE When considering the mechanism of protein-ligand binding, the concept of conformational capture suggests that the conformation of the protein required for ligand binding exists as one of many nearly isoenergetic conformational states. TRUE FALSE

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter9: Cell Communication

Section: Chapter Questions

Problem 12RQ: Histamine binds to the H1 G-protein-linked receptor to initiate the itchiness and airway...

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At any given time, intestinal crypts of mice com-prise about 15 stem cells and 10 Paneth cells. After celldivision, which occurs about once a day, the daughtercells remain stem cells only if they maintain contact with aPaneth cell. This constant competition for Paneth-cell con-tact raises the possibility that crypts might become mono-clonal over time; that is, the crypt cells at one point in timemight derive from only 1 of the 15 stem cells that existedat some earlier time. To test this possibility, you use theso-called confetti marker that upon activation expressesany one of three fluorescent proteins in the stem cells ofthe crypt. You then examine crypts at various times todetermine whether they contain cells with multiple colorsor only one color (Figure Q22–1). Do the crypts becomemonoclonal over time or not? How can you tell?
In 1994, the U.S. Public Health Service identified “10 Essential Public Health Services.” For each of the ten, briefly describe a specific activity that has been used in the response to COVID-19.
The white blood cells known as T lymphocytes respond to antigens thatbind specifi cally to the T cell receptor, which consists of an antigen-binding αβ transmembrane protein as well as a set of transmembrane signaltransducing proteins known as CD3 that are targets of NRTKs. Thecytoplasmic domains of the CD3 proteins are positively charged and, in the absence of antigen, interact with the intracellular surface of the plasma membrane in such a way that buries several of their Tyr residues in the lipidbilayer. Antigen binding to the T cell receptor leads to a localized infl ux ofCa2+ ions. (a) Explain how a high concentration of Ca2+ could promote phosphorylation and activation of the CD3 proteins. (b) Would this henomenon make the T lymphocyte more or less responsive to the antigen?
What effect does a negative effector have on the graph of reac- tion rate (V) vs. [substrate] for an allosteric effector?
Cite evidence supporting a long evolutionary history for cell signaling molecules.
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It is not an easy matter to assign particular func-tions to specific components of the basal lamina, sincethe overall structure is a complicated composite materialwith both mechanical and signaling properties. Nidogen,for example, cross-links two central components of thebasal lamina by binding to the laminin γ-1 chain and totype IV collagen. Given such a key role, it was surprisingthat mice with a homozygous knockout of the gene fornidogen-1 were entirely healthy, with no abnormal phe-notype. Similarly, mice homozygous for a knockout of thegene for nidogen-2 also appeared completely normal. Bycontrast, mice that were homozygous for a defined muta-tion in the gene for laminin γ-1, which eliminated just thebinding site for nidogen, died at birth with severe defectsin lung and kidney formation. The mutant portion of thelaminin γ-1 chain is thought to have no other functionthan to bind nidogen, and does not affect laminin struc-ture or its ability to assemble into the basal lamina.…
The affinity of integrins for matrix components canbe modulated by changes to their cytoplasmic domains:a process known as inside-out signaling. You have iden-tified a key region in the cytoplasmic domains of αIIbβ3integrin that seems to be required for inside-out signaling(Figure Q19–3). Substitution of alanine for either D723in the β chain or R995 in the α chain leads to a high levelof spontaneous activation, under conditions where thewild-type chains are inactive. Your advisor suggests thatyou convert the aspartate in the β chain to an arginine(D723R) and the arginine in the α chain to an aspartate(R995D). You compare all three α chains (R995, R995A,and R995D) against all three β chains (D723, D723A, andD723R). You find that all pairs have a high level of sponta-neous activation, except D723 vs R995 (the wild type) andD723R vs R995D, which have low levels. Based on theseresults, how do you think the αIIbβ3 integrin is held in itsinactive state?
Much of what we know about cellsignaling comes from biochemicalstudies of isolated proteins in testtubes. What is the precise quantitativebehavior of intracellular signalingnetworks in an intact cell, or in anintact animal, where countless othersignals and cell components mightinfluence signaling specificity andstrength?
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"given the numerous processes inside cells that are regulated by changes in Ca+2 concentration, it seems likely that Ca¹²-dependent cell-cell adhesions are also regulated by changes in Ca2 concentration" is true or false.
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