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Cooperativity
About: Cooperativity is a research topic. Over the lifetime, 7027 publications have been published within this topic receiving 258930 citations. The topic is also known as: cooperativity.
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619 citations
TL;DR: It is shown that allostery can be mediated exclusively by transmitted changes in protein motions, and this work characterized the negatively cooperative binding of cAMP to the dimeric catabolite activator protein (CAP) at discrete conformational states.
Abstract: Allosteric interactions are typically considered to proceed through a series of discrete changes in bonding interactions that alter the protein conformation. Here we show that allostery can be mediated exclusively by transmitted changes in protein motions. We have characterized the negatively cooperative binding of cAMP to the dimeric catabolite activator protein (CAP) at discrete conformational states. Binding of the first cAMP to one subunit of a CAP dimer has no effect on the conformation of the other subunit. The dynamics of the system, however, are modulated in a distinct way by the sequential ligand binding process, with the first cAMP partially enhancing and the second cAMP completely quenching protein motions. As a result, the second cAMP binding incurs a pronounced conformational entropic penalty that is entirely responsible for the observed cooperativity. The results provide strong support for the existence of purely dynamics-driven allostery.
604 citations
TL;DR: It is likely that the insulin receptors exist as oligomeric structures or clusters in the plasma membrane as well as in human circulating monocytes and human cultured lymphocytes demonstrated negative cooperativity that was extraordinarily simn membranes more slowly than it does from its receptors on whole cells.
591 citations
Book•
01 Jan 1990TL;DR: Allosteric membrane proteins are studied as indicators of allosteric equilibrium on spin state and coordination of the haem iron and of feedback inhibition without change of quaternary structure in E. Coli repressors.
Abstract: Preface 1. Introduction 2. Haemoglobin: Dependence of allosteric equilibrium on spin state and coordination of the haem iron 3. Haemocyanin: Dependence of allosteric equilibrium on coordination and valency of a binuclear copper complex 4. Haemerythrin: Cooperativity in a binuclear iron complex 5. Glycogen phosphorylase: Control of glycolysis 6. Phosphofructokinase: Further control of glycolysis 7. Feedback inhibition of a biosynthetic pathway: Aspartate Transcarbamoylase 8. Control of nitrogen metabolism: Glutamine synthetase 9. Cooperativity and feedback inhibition without change of quaternary structure: The "trp" and "met" repressors of E. Coli 10. Immunoglobulins: Cooperative binding to multivalent antigens 11. Allosteric membrane proteins.
548 citations
TL;DR: Models are presented that show how sequential NTP hydrolysis can lead to unidirectional and processive translocation and possible unwinding mechanisms based on the DNA exclusion model are proposed here, termed the wedge, torsional, and helix-destabilizing models.
Abstract: Helicases are motor proteins that couple the hydrolysis of nucleoside triphosphate (NTPase) to nucleic acid unwinding. The hexameric helicases have a characteristic ring-shaped structure, and all, except the eukaryotic minichromosomal maintenance (MCM) helicase, are homohexamers. Most of the 12 known hexameric helicases play a role in DNA replication, recombination, and transcription. A human genetic disorder, Bloom's syndrome, is associated with a defect in one member of the class of hexameric helicases. Significant progress has been made in understanding the biochemical properties, structures, and interactions of these helicases with DNA and nucleotides. Cooperativity in nucleotide binding was observed in many, and sequential NTPase catalysis has been observed in two proteins, gp4 of bacteriophage T7 and rho of Escherichia coli. The crystal structures of the oligomeric T7 gp4 helicase and the hexamer of RepA helicase show structural features that substantiate the observed cooperativity, and both are consistent with nucleotide binding at the subunit interface. Models are presented that show how sequential NTP hydrolysis can lead to unidirectional and processive translocation. Possible unwinding mechanisms based on the DNA exclusion model are proposed here, termed the wedge, torsional, and helix-destabilizing models.
543 citations