Name: allosteric changes in protein shape
Uploaded: 2023-04-30T18:28:43.000Z
Duration: 1 min 58 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

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

From Molecules to Organisms: Structures and Processes

HS-LS1-1

Cooperative Allosteric Transitions

у многих белков есть несколько подъединиц где каждая подъединица содержит отдельный узел связывания лигандов. Когда молекула, известная как модулятор, привязывается к одной из подъединиц, она запускает конформационные изменения в местах привязки других подразделений, изменение их родства для соответствующих лигандов. Это называется кооперативным аллостерическим переходом и его можно объяснить с помощью нескольких теоретических моделей.Согласованные, или все модели, или ни одна модель предполагает, что все подразделения существуют вместе или в положении off"или on"Связывание может произойти в любом положении. Однако, состояние on"имеет более высокий уровень сродства для лиганда чем состояние off"Когда связывается лиганд в любой из подгрупп, она поддерживает одновременную трансформацию всех обязательных сайтов к форме с высокой степенью сродства. Кооперативность может быть также разъяснена с помощью последовательной модели, которая предполагает, что каждая подъединица может существовать независимо в состоянии высокого или низкого сродства, но скорее всего в состоянии с высокой степенью сродства когда связывается лиганд любой из подгрупп.Сайты связывания аллостерических белков обычно представляют собой смесь гибких и фиксированных сегментов цепи аминокислот. Когда связывается лиганд, эти нестабильные части стабилизируются в особую конформацию. И это влияет на форму сайтов связывания других подъединиц.Гемоглобин является примером тетрамерного белка, который проходит кооперативный аллостерический переход, когда связывается кислород. Каждая подъединица гемоглобина имеет один сайт связывания. Когда одна молекула кислорода привязывается к одной подъединице, кооперативно увеличивая сродство к кислороду на оставшихся сайтах связывания, облегчая для кислорода привязку к молекуле гемоглобина, к которой уже привязан кислород.

<ol>
	<li>Корниш-Боуден, А. (2014), Понимание аллостерических и кооперативных взаимодействий в ферментах. FEBS J, 281: 621-632. DOI:10.1111/фев.12469</li>
	<li>Альбертс и др., 6-е издание; стр. 152-153</li>
	<li>Принципы биохимии Ленингера, 5-е издание, стр. 162,165</li>
</ol>

Кооперативные аллостерические переходы

Кооперативные аллостерические переходы могут происходить в мультимерных белках, где каждая субъединица белка имеет собственный сайт связывания лиганда. Когда лиганд связывается с любой из этих субъединиц, он вызывает конформационные изменения, которые влияют на сайты связывания в других субъединицах; это может изменить сродство других сайтов к соответствующим лигандам. Способность белка изменять форму своего сайта связывания объясняется наличием в структуре смеси гибких и стабильных сегментов. Молекула, которая запускает это изменение, известна как модулятор. Для объяснения кооперативности в мультимерных белках часто используются две модели: согласованная и последовательная модель. Согласованная модель, также известная как модель «все или ничего», предполагает, что все субъединицы мультимерного белка одновременно переключаются между конформациями «включено» и «выключено». Во «включенной» форме сайты связывания имеют высокое сродство к соответствующим лигандам, а во «выключенной» форме сайты связывания имеют низкое сродство. Когда лиганд связывается с любой из субъединиц, он способствует переходу в высокоаффинную форму, одновременно изменяя конформацию всех других сайтов связывания белка. Хотя лиганд может связываться с любой формой, ему легче связываться в форме с высоким сродством. Последовательная модель предполагает, что каждая субъединица мультимерного белка может существовать независимо во «включенной» или «выключенной» конформации, то есть в форме с низким или высоким сродством, независимо от состояния других субъединиц. Связывание лиганда с субъединицей изменяет равновесие между формами с низким и высоким сродством, так что субъединица с большей вероятностью будет находиться в форме с высоким сродством. Кроме того, связывание лиганда с одной субъединицей смещает равновесие других субъединиц белка. Это увеличивает вероятность того, что после связывания одного лиганда другой лиганд свяжется с другой субъединицей. Эта кооперативность увеличивает чувствительность белка к концентрации лиганда. Связывание лиганда в одном сайте может изменить сродство всей молекулы белка, тем самым обеспечивая быстрый ответ при низких концентрациях.

Кооперативные аллостерические переходы могут происходить в мультимерных белках, где каждая субъединица белка имеет свой собственный сайт связывания лигандов. Когда лиганд ...

Education

JoVE Core

Cell Biology

Клеточная биология

Unit 1

Раздел 1

Protein Function

Функции белков

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

allosteric changes in protein shape

Allosteric changes in protein shape help explain how some proteins switch between active and inactive states. These transitions are cooperative, which means a change in one part of the protein can affect other parts of the same molecule.

The video focuses on how these shifts in shape support protein function. It also shows that allosteric transitions can be described with different models. In the concerted model, the protein changes shape as a whole. In the sequential model, the change happens step by step across the protein.

These models help students understand how proteins respond to signals in the cell. They also show why protein shape is closely linked to biological activity.

Allosteric Changes in Protein Shape

ligand binding sites

Ligand Binding Sites in Proteins

Ligand binding sites are specific parts of a protein where a ligand can attach. A ligand is a molecule that binds to another molecule, often to help start or change a biological process. These sites matter because the shape and chemistry of the protein help determine which ligands can fit and bind. Proteins do not bind every ligand in the same way. The binding site provides a matching surface that supports a close interaction. In many cases, this interaction is important for how cells respond...

protein-protein interfaces

Protein Binding Surfaces and Contacts

Protein binding surfaces and contacts help proteins recognize and attach to each other. These interfaces are the regions where two proteins meet and interact. They are important for many cell processes and for how proteins work together. A protein-protein interface is not just a random touch point. It is shaped by the three-dimensional form of each protein. The matching surfaces allow a stable interaction to form when the proteins fit together well. Studying these interfaces helps explain how...

conserved binding sites

Conserved Binding Sites in Protein Families

Conserved binding sites are regions on proteins that stay similar across related proteins. These shared areas often help proteins interact with the same molecules. For this reason, they are useful clues when comparing protein families. A conserved site can help identify where a protein binds. It can also show which parts of the protein are important for function. When the same pattern appears in several proteins, it suggests that the site has been kept through evolution. Scientists look at...

cofactors and coenzymes

Enzyme Helpers: Metals and Vitamins

Enzyme helpers include cofactors and coenzymes. Enzymes are proteins made of amino acids, and the functional groups on those amino acids can drive many chemical reactions through ionic interactions or acid-base reactions. But amino acids alone cannot handle oxidation-reduction and group transfer reactions, so they need non-protein helpers called cofactors. Cofactors are often described as the chemical teeth of an enzyme. They can be metal ions or organic molecules called coenzymes. These...

cooperative allosteric transitions

Allosteric changes in protein shape help explain how some proteins switch between active and inactive states. These transitions are cooperative, which means a change in one part of the protein can affect other parts of the same molecule. The video focuses on how these shifts in shape support protein function. It also shows that allosteric transitions can be described with different models. In the concerted model, the protein changes shape as a whole. In the sequential model, the change happens...

protein kinases and phosphatases

Protein Kinases and Phosphatases in Cell Control

Protein kinases and phosphatases help control how proteins work in cells. Kinases add phosphate groups to proteins. Phosphatases remove those phosphate groups. This phosphorylation and dephosphorylation process can change a protein’s shape and activity. It is one way cells turn protein function on or off at the right time. These changes also help cells respond to signals and manage many cell activities. Together, protein kinases and phosphatases keep cellular signaling balanced. When one adds...

gtpases and their regulation

GTPase Molecular Switches and Control

GTPases are molecular switches that help control cell activity. They bind guanosine triphosphate, or GTP, and can change between active and inactive states. This switch-like behavior makes them important in many cell processes. The protein is active when GTP is bound and inactive when guanosine diphosphate, or GDP, is bound. GTPases can also turn themselves off by breaking down GTP into GDP. This built-in control helps cells regulate when the protein is on or off. Their activity is regulated...

covalently linked protein regulators

Protein Regulation by Covalent Bonds

Protein regulation by covalent bonds helps control how cells respond to changing conditions. A covalent bond is a strong chemical link, and in this context it can change how a protein behaves. Some regulators work by attaching a chemical group directly to a protein. This covalent change can alter the protein's activity, its location in the cell, or how long it stays active. Because the change is built into the protein itself, it can have a strong effect on cell function. Covalently linked...

protein complexes with interchangeable parts

protein-complexes-with-interchangeable-parts

Modular Protein Complexes in Cells

Protein complexes in cells can be built from interchangeable parts. This modular design lets some complexes share common subunits while still changing their behavior. A well-known example is the ubiquitin ligase complex called SCF. SCF stands for Skp1-Cullin-F-box, and it helps attach ubiquitin, a small protein tag, to target proteins. The core of SCF stays the same, but the F-box protein can change. The interchangeable F-box subunit gives the complex its specificity. Different F-box proteins...

mechanical protein function

Proteins That Generate Cell Movement

Mechanical proteins help cells and tissues move. They turn chemical energy into force and motion. This process is important in many biological systems. These proteins are also called motor proteins. They interact with cell structures and can produce directed movement. In muscle cells, they support contraction. In other cells, they help with transport and shape changes. Mechanical protein function is a key part of how living systems work. It links protein activity to movement at the cellular...

structural protein function

Structural Proteins in Cells and Tissues

Structural proteins help cells and tissues keep their shape and strength. They are an important part of living systems because they provide support where it is needed most. Many structural proteins form fibers or other sturdy forms that resist stretching and wear. These proteins work as building materials in the body and help keep structures stable over time. Examples of structural proteins include collagen, actin, myosin, and keratin. Each one supports a different part of the body, but all...

protein networks

Mapping Protein Interaction Networks

Protein interaction networks show how proteins work together inside a cell. These networks help scientists see which proteins connect with each other and how those links support cell activity. Researchers often use online tools to build and study these networks. The transcript points to IntAct and STRING as examples of resources that can help predict and organize protein interactions. These tools make it easier to compare protein links and look for patterns in the network. Protein networks...

key terms and concepts

Explore cooperative allosteric transitions and learn how protein shape changes can switch proteins between active and inactive states using concerted and sequential models.

Allosteric Changes in Protein Shape | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

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Structural Protein Function

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HS-LS1-2

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HS-LS1-3

Allosteric Changes in Protein Shape

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