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

많은 단백질에는 여러 개의 소단위가 있으며, 각 소단위에는 별도의 리간드 결합 부위가 포함되어 있습니다.
조절자(modulator)로 알려진 분자가 소단위체 중 하나에 결합하면 다른 소단위체의 결합 부위에 구조적 변화가 일어나 각각의 리간드에 대한 친화력이 변경됩니다. 이를 협력 알로스테릭 전이(cooperative allosteric transition)라고 하며 몇 가지 이론적 모델로 설명할 수 있습니다.
concerted 또는 "all-or-none" 모델은 모든 소단위가 "off" 또는 "on" 형태로 함께 존재한다고 가정합니다.
결합은 두 가지 형태 모두에서 발생할 수 있지만 "켜짐" 상태는 "꺼짐" 상태보다 리간드에 대한 친화도가 더 높습니다. 리간드가 소단위 중 하나에서 결합하면 모든 결합 부위가 친화도가 높은 형태로 동시에 변환되는 것을 촉진합니다.
협력성은 또한 각 소단위가 높거나 낮은 친화도 상태에서 독립적으로 존재할 수 있다고 가정하는 순차 모델에 의해 설명될 수 있지만, 리간드가 소단위 중 하나에 결합될 때 높은 친화도 상태에 있을 가능성이 더 높습니다. 
알로스테릭 단백질의 결합 부위는 일반적으로 아미노산 사슬의 유연하고 고정된 부분이 혼합되어 있습니다. 리간드가 결합할 때 이러한 불안정한 부분은 특정 형태로 안정화되며, 이는 다른 소단위체의 결합 부위 모양에 영향을 미칩니다. 
헤모글로빈(Hemoglobin)은 산소가 결합할 때 협력 알로스테릭 전이를 겪는 사량체 단백질의 한 예입니다.
헤모글로빈의 각 소단위체에는 단일 결합 부위가 있습니다. 하나의 산소 분자가 단일 소단위체에 결합할 때, 협력성은 나머지 결합 부위의 산소에 대한 친화력을 증가시켜 산소가 이미 산소와 결합된 헤모글로빈 분자에 더 쉽게 결합할 수 있도록 합니다.

<ol>
	<li>Cornish‐Bowden, A. (2014), 효소의 알로스테릭 및 협력 상호 작용 이해. 2월 J, 281: 621-632. 도이 : 10.1111 / febs.12469</li>
	<li>Alberts et al., 6판; 152-153페이지</li>
	<li>Lehninger Principles of Biochemistry, 5판, 162,165페이지</li>
</ol>

협력 알로스테릭 전이

협력적 알로스테릭 전이는 단백질의 각 소단위체가 자체 리간드 결합 부위를 갖는 다양체 단백질에서 발생할 수 있습니다. 리간드가 이러한 손단위체 중 하나에 결합하면 다른 소단위체의 결합 부위에 영향을 미치는 형태 변화를 유발합니다. 이는 해당 리간드에 대한 다른 사이트의 친화력을 변경할 수 있습니다. 결합 부위의 모양을 바꾸는 단백질의 능력은 구조에 유연하고 안정적인 부분이 혼합되어 있기 때문입니다. 이러한 변화를 촉발하는 분자를 조절물질(modulator)이라고 합니다.

다중 단백질의 협동성을 설명하기 위해 종종 두 가지 모델, 즉 협력 모델과 순차 모델이 사용됩니다. 전부 아니면 전무 모델로도 알려진 공동 모델은 다양체 단백질의 모든 소단위제가 "켜짐"과 "꺼짐" 형태 사이에서 동시에 전환된다는 가설을 세웁니다. "켜짐" 형태에서는 결합 부위가 해당 리간드에 대해 높은 친화성을 갖고, "꺼짐" 형태에서는 결합 부위의 친화성이 낮습니다. 리간드가 소단위체 중 하나에 결합하면 친화력이 높은 형태로의 전환을 촉진하고 동시에 단백질의 다른 모든 결합 부위의 형태를 변경합니다. 리간드는 어느 형태에든 결합할 수 있지만 친화력이 높은 형태일 때 결합하기가 더 쉽습니다.

순차 모델은 다양체 단백질의 각 손다위체가 다른 소단위체의 상태에 관계없이 "켜짐" 또는 "꺼짐" 구조, 즉 친화도가 낮거나 높은 형태로 독립적으로 존재할 수 있다고 가정합니다. 소단위체에 대한 리간드의 결합은 하위 단위가 높은 친화도 형태일 가능성이 더 높도록 낮은 친화도 형태와 높은 친화도 형태 사이의 평형을 변경합니다. 또한, 한 소단위체에 결합된 리간드는 단백질의 다른 하위 단위에 대한 평형을 이동시킵니다. 이는 하나의 리간드가 결합되면 다른 리간드가 다른 소단위체에 결합할 가능성을 증가시킵니다. 이러한 협력성은 리간드 농도에 대한 단백질의 민감도를 증가시킵니다. 단일 부위의 리간드 결합은 전체 단백질 분자의 친화력을 변화시켜 낮은 농도에서도 빠른 반응을 가능하게 합니다.

협력 알로스테릭 전이는 다중체 단백질에서 발생할 수 있으며, 단백질의 각 소단위에는 자체 리간드 결합 부위가 있습니다. 리간드가 ...

Education

교육

JoVE Core

Cell Biology

세포생물학

Unit 1

제1단원

Protein Function

단백질 기능

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

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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

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HS-LS1-2

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HS-LS1-3

Allosteric Changes in Protein Shape

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