Name: how proteins shift shape together
Uploaded: 2023-04-30T18:28:42.000Z
Duration: 1 min 58 s
Channel: JoVE

K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms- Structures and Processes

LS.Bio.1.2

Cooperative Allosteric Transitions

Many proteins have multiple subunits, where each subunit contains a separate ligand binding site.
When a molecule, known as a modulator, binds to one of the subunits it triggers a conformational change in the binding sites of the other subunits changing their affinity for their respective ligands. This is called a cooperative allosteric transition and can be explained by several theoretical models.
The concerted or &#8220;all-or-none&#8221; model assumes that all of the subunits exist together in either an &#8220;off&#8221; or &#8220;on&#8221; conformation.
Binding can occur in either form, however, the &#8220;on&#8221; state has a higher affinity for the ligand than the &#8220;off&#8221; state. When a ligand binds at any of the subunits, it promotes the simultaneous transformation of all of the binding sites to the high-affinity form.
Cooperativity can also be explained by the sequential model, which assumes that each subunit can exist independently in a high or low-affinity state, but is more likely to be in the high-affinity state when the ligand is bound to any of the subunits.&#160;
The binding sites of allosteric proteins are usually a mix of flexible and fixed segments of the amino acid chain. When a ligand binds, these unstable parts are stabilized in a particular conformation, and this affects the shape of the binding sites on the other subunits.&#160;
Hemoglobin is an example of a tetrameric protein that undergoes a cooperative allosteric transition when oxygen binds.
Each subunit of hemoglobin has a single binding site. When one molecule of oxygen binds to a single subunit, cooperativity increases the affinity for oxygen on the remaining binding sites making it easier for oxygen to bind to a molecule of hemoglobin that already has oxygen bound to it.&#160;

cooperative allosteric transitions

Coöperatieve allosterischeallostere transities kunnen voorkomenoptreden in multimeremultimerische eiwitten, waarbij elke subeenheid van het eiwit zijneen eigen ligandbindingsplaats heeft. Wanneer een ligand aan een van deze subeenheden bindt, veroorzaakt dit een conformationele verandering die de bindingsplaatsen in de andere subeenheden beïnvloedt; dit kan en de affiniteit van de andere plaatsen voor hun respectieve liganden kan veranderen. Het vermogen van het eiwit om de vorm van zijn bindingsplaats te veranderen, wordt toegeschreven aan de aanwezigheid van een mix van flexibele en stabiele segmenten in de structuur. Een molecuul dat deze verandering teweegbrengt, staat bekend alswordt een modulator genoemd.

Er Twee modellen worden vaak twee modellen gebruikt om de coöperativiteit in multimeremultimerische eiwitten te verklaren: het gecoördineerdeconcertmodel en het sequentiële model. 

Het gecoördineerde modelconcertmodel, ook bekend als het alles-of-niets-model, veronderstelt dat alle subeenheden van een multimeermultimerisch eiwit gelijktijdig schakelen tussen de "aan""- en "uit" "-conformaties. In de “"aan”-"-vorm hebben de bindingsplaatsen een hoge affiniteit voor hun respectievelijkerespectieve liganden, en in de “"uit”-"-vorm hebben de bindingsplaatsenze een lage affiniteit. Wanneer een ligand aan een van de subeenheden bindt, bevordert hetdit de omzetting naar de vorm met hoge affiniteit, waardoor -affiniteitvorm en verandert het tegelijkertijd de conformatie van alle andere bindingsplaatsen vanin het eiwit verandert. Hoewel een ligand aan beide vormen kan binden, is het gemakkelijker voor het ligand om te binden wanneer het eiwit zich in de vorm met hoge affiniteit-affiniteitvorm bevindt.

Het sequentiële model gaat ervan uit dat elke subeenheid van een multimeermultimerisch eiwit onafhankelijk kan bestaan in een “"aan”"- of “"uit” "-conformatie, dat wil zeggen in de vorm met lage- of hoge affiniteit-affiniteitvorm, ongeacht de toestand van de andere subeenheden. BindingDe binding van een ligand aan een subeenheid verandert het evenwicht tussen de vormen met lage- en hoge affiniteit zodanig dat het waarschijnlijker is-affiniteitvormen, waardoor de kans groter wordt dat de subeenheid zich in de vorm met hoge affiniteit-affiniteitvorm bevindt. Bovendien verschuift de binding van een ligandbinding aanligand op één subeenheid het evenwicht voor de andere subeenheden in het eiwit. Dit vergrootverhoogt de kanswaarschijnlijkheid dat zodra één ligand is gebonden, een ander ligand zich aan een andere subeenheid zal binden. Deze coöperativiteit verhoogt de gevoeligheid van het eiwit voor de ligandconcentratie. Een , waardoor een enkele ligandbinding op een enkele plaats kan de affiniteit voorvan het gehelehele eiwitmolecuul kan veranderen, waardoor en een snelle respons bij lage concentraties mogelijk wordt.maakt.

Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand ...

Education

JoVE Core

Cell Biology

Celbiologie

Unit 1

Eenheid 1

Energy and Catalysis

Energie en Katalyse

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Coöperatieve allosterische overgangen

how proteins shift shape together

Proteins can change shape in a coordinated way during allosteric transitions. In a cooperative transition, one part of the protein affects another part, so the change spreads through the molecule.

These shape changes help proteins switch between different states. The shift can influence how the protein works and how it responds to other molecules.

Cooperative allosteric transitions are an important idea in protein function. They explain how a small change at one site can lead to a larger change across the protein structure.

How Proteins Shift Shape Together

the first law of thermodynamics

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the-equilibrium-binding-constant-and-binding-strength

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Proteins can change shape in a coordinated way during allosteric transitions. In a cooperative transition, one part of the protein affects another part, so the change spreads through the molecule. These shape changes help proteins switch between different states. The shift can influence how the protein works and how it responds to other molecules. Cooperative allosteric transitions are an important idea in protein function. They explain how a small change at one site can lead to a larger...

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key terms and concepts

Explore cooperative allosteric transitions and how protein shape changes can spread through a molecule to affect protein function in high school biology.

How Proteins Shift Shape Together | JoVE K12

cell biology

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Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.c

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.4

SC.912.L.18.11

Texas Essential Knowledge and Skills

BIO.11

BIO.11.B

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LS.Bio.1.1

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Analyze how the relationship between structure and function supports life processes within organisms.

How Proteins Shift Shape Together

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