Name: protein regulation by covalent bonds
Uploaded: 2023-04-30T18:28:43.000Z
Duration: 2 min 4 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

Covalently Linked Protein Regulators

Viele Proteine werden durch kovalent verknüpfte Moleküle reguliert, darunter funktionelle Gruppen wie Methyl- oder Acetyleinheiten und kleine Proteine wie Ubiquitin.
Kovalente Bindungen treten an spezifischen Aminosäuren in der Polypeptidkette auf. Zum Beispiel sind Phosphatgruppen kovalent an Serin, Threonin oder Tyrosin gebunden; Methyl- und Acetylgruppen sind an Lysin gebunden; und Ubiquitin ist mit Lysin-, Cystein-, Serin- oder Threoninresten verbunden.
Ein Enzym oder ein Paar von Enzymen katalysiert reversibel diese posttranslationalen Modifikationen. Eine Acetyltransferase kann ein Protein acetylieren, während eine Deacetylase die Gruppe später entfernen kann.
Diese Modifikationen können die Funktion oder die Lokalisation eines Proteins in einer Zelle verändern.
Zum Beispiel reguliert die Acetylierung von Histonproteinen die Genexpression, indem sie die DNA-Struktur öffnet, um die Gentranskription zu aktivieren. Andererseits ist bekannt, dass die Methylierung von Histonproteinen die Transkription unterdrückt, indem sie die Struktur strafft. 
Ein weiteres Beispiel ist p53, ein Multidomänen-Tumorsuppressorprotein, das als Reaktion auf Stress mehrere kovalente Modifikationen durchläuft. Die Exposition gegenüber DNA-schädigenden Stoffen wie UV- und Gammastrahlung kann zu einer Phosphorylierung des Proteins führen. 
Die Phosphorylierung verbessert die Stabilität und aktiviert p53, wodurch es an die durch die Strahlung geschädigte DNA bindet und Zellen mit mutierter DNA sich unkontrolliert teilen.
Zusätzlich zur Phosphorylierung ermöglichen verschiedene Arten von Modifikationen, die an einem einzelnen Proteinmolekül auftreten, wie z. B. p53, die genaue Kontrolle seiner Funktionen wie Zellzyklusarrest, DNA-Reparatur und Apoptose einer Zelle.

<ol>
	<li>1PDB-Kennung: 1UBQ 
	Vijay-Kumar, S., Bugg, C.E., Cook, WJ (1987) Struktur von Ubiquitin raffiniert bei einer Auflösung von 1,8 A. J Mol Biol 194: 531-544. DOI: 10.1016/0022-2836(87)90679-6</li>
	<li>H.M. Berman, J. Westbrook, Z. Feng, G. Gilliland, T.N. Bhat, H. Weissig, I.N. Shindyalov, P.E. Bourne. (2000) Die Proteindatenbank Nukleinsäureforschung, 28: 235-242.</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol*: Auf dem Weg zu einer gemeinsamen Bibliothek und Tools für die Web-Molekulargrafik MolVA/EuroVis Proceedings. doi:10.2312/molva.20181103</li>
	<li>Alberts et al., 6. Auflage; Seiten 157-158, 165-166</li>
	<li>Le, D. D., & Fujimori, D. G. (2012). Protein- und Nukleinsäure-methylierende Enzyme: Mechanismen und Regulierung. Aktuelle Meinung in der chemischen Biologie, 16(5-6), 507–515. doi:10.1016/j.cbpa.2012.09.014</li>
	<li>Khidekel, N., & Hsieh-Wilson, L. C. (2004). Eine "molekulare Schalttafel" – kovalente Modifikationen von Proteinen und ihre Auswirkungen auf die Transkription. Organische und biomolekulare Chemie, 2(1), 1-7.</li>
	<li>Maclaine, N. J., & Hupp, T. R. (2009). Die Regulation von p53 durch Phosphorylierung: ein Modell dafür, wie sich unterschiedliche Signale in den p53-Signalweg integrieren. Altern, 1(5), 490.</li>
</ol>

kovalent verknüpfte proteinregulatoren

Proteine können viele Arten von posttranslationalen Modifikationen durchlaufen, oft als Reaktion auf Veränderungen in ihrer Umgebung. Diese Modifikationen spielen eine wichtige Rolle bei der Funktion und Stabilität dieser Proteine. Zu den kovalent gebundenen Molekülen gehören funktionelle Gruppen wie Methyl-, Acetyl- und Phosphatgruppen sowie kleine Proteine wie Ubiquitin. Es wurden etwa 200 verschiedene Arten von kovalenten Regulatoren identifiziert.

Diese Gruppen modifizieren spezifische Aminosäuren in einem Protein. Phosphatgruppen können nur kovalent an die Aminosäuren Serin, Threonin und Tyrosin gebunden werden, während Methyl- und Acetylgruppen nur an Lysin gebunden werden können. Diese Gruppen werden durch ein Enzym oder ein Paar von Enzymen zu einem Protein hinzugefügt und entfernt. Zum Beispiel fügt eine Acetyltransferase eine Acetylgruppe zu einem Protein hinzu, und eine Deacetylase kann sie entfernen. Jeder dieser Modifikatoren kann unterschiedliche Auswirkungen auf das Protein haben, an das er angehängt ist, abhängig von der Anzahl und Lage der Modifikationen. Wenn ein einzelnes Ubiquitin-Molekül kovalent an einen bestimmten Zelloberflächenrezeptor gebunden wird, wird dieses Protein für die Endozytose markiert; andererseits wird es als Ziel für den proteolytischen Abbau markiert, wenn mehrere zusammenhängende Ubiquitine daran befestigt sind.

Ein einzelnes Protein kann gleichzeitig mehrere Modifikationen durchlaufen, um seine Funktion zu steuern. Ein bekanntes Beispiel für ein Protein, das durch mehrere kovalente Modifikationen reguliert wird, ist das Tumorsuppressor-Protein p53. p53 erfährt eine Vielzahl von Modifikationen als Reaktion auf verschiedene Arten von Stress, einschließlich Strahlung und Karzinogenen. Einige Modifikationen umfassen Phosphorylierung, Acetylierung und Sumoylierung als Reaktion auf UV- und Gammastrahlung. Die Stellen und Arten der Modifikationen können je nach Stressfaktor variieren. Studien haben gezeigt, dass UV- und Gammastrahlung zur Phosphorylierung von Serin 33 führen kann, aber Serin 392 kann bei Exposition gegenüber UV-Strahlung, jedoch nicht bei Gammastrahlung phosphoryliert werden. Andere Arten von Stress, wie die Exposition gegenüber Hypoxie, Antimetaboliten und Actinomycin D, können zur Acetylierung von p53 führen. Die Modifikationen können auch zwischen verschiedenen Zelltypen und Organismen variieren.

Kovalent verknüpfte Proteinregulatoren

Proteine können viele Arten von posttranslationalen Modifikationen durchlaufen, oft als Reaktion auf Veränderungen in ihrer Umgebung. Diese Modifikationen spielen eine ...

Education

Lehre

JoVE Core

Cell Biology

Zellbiologie

Unit 1

Einheit 1

Protein Function

Proteinfunktion

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

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 regulators are an important part of cell control and signaling. They help cells turn protein functions on or off at the right time. This type of regulation is a key idea in molecular biology and protein function.

Protein Regulation by Covalent Bonds

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

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conserved binding sites

Conserved Binding Sites in Protein Families

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cofactors and coenzymes

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cooperative allosteric transitions

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...

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 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

Learn how covalent bonds can regulate proteins by changing activity, location, and stability. A clear K12 summary of protein control in cells.

Protein Regulation by Covalent Bonds | JoVE K12

cell biology

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HS-LS1-2

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HS-LS1-3

Protein Regulation by Covalent Bonds

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