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

Wiele białek jest regulowanych przez kowalencyjnie połączone cząsteczki, w tym grupy funkcyjne, takie jak ugrupowania metylowe lub acetylowe, oraz małe białka, takie jak ubikwityna.
Wiązania kowalencyjne występują na określonych aminokwasach w łańcuchu polipeptydowym. Na przykład grupy fosforanowe są kowalencyjnie związane z seryną, treoniną lub tyrozyną; grupy metylowe i acetylowe są związane z lizyną; a ubikwityna jest powiązana z resztami lizyny, cysteiny, seryny lub treoniny.
Enzym lub para enzymów odwracalnie katalizuje te modyfikacje potranslacyjne. Acetylotransferaza może acetylować białko, podczas gdy deacetylaza może później usunąć grupę.
Modyfikacje te mogą zmienić funkcję lub lokalizację białka w komórce.
Na przykład acetylacja białek histonowych reguluje ekspresję genów poprzez otwarcie struktury DNA w celu aktywacji transkrypcji genów. Z drugiej strony wiadomo, że metylacja białek histonowych hamuje transkrypcję poprzez zaciśnięcie struktury. 
Innym przykładem jest p53, wielodomenowe białko supresorowe nowotworu, które ulega kilku kowalencyjnym modyfikacjom w odpowiedzi na stres. Narażenie na czynniki uszkadzające DNA, takie jak promieniowanie UV i gamma, może powodować fosforylację białka. 
Fosforylacja poprawia stabilność i aktywuje p53, powodując jego wiązanie się z DNA uszkodzonym przez promieniowanie i zapobiega niekontrolowanemu podziałowi komórek ze zmutowanym DNA.
Oprócz fosforylacji, różne rodzaje modyfikacji zachodzących na pojedynczej cząsteczce białka, takiej jak p53, pozwalają jej precyzyjnie kontrolować jej funkcje, takie jak zatrzymanie cyklu komórkowego, naprawa DNA i apoptoza komórki.

<ol>
	<li>1identyfikator PDB: 1UBQ 
	Vijay-Kumar, S., Bugg, CE, Cook, WJ (1987) Struktura ubikwityny rafinowana w rozdzielczości 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) Badania kwasów nukleinowych w Banku Danych o Białkach, 28: 235-242.</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol*: W kierunku wspólnej biblioteki i narzędzi do internetowej grafiki molekularnej MolVA/EuroVis Proceedings. doi:10.2312/molva.20181103</li>
	<li>Alberts et al., wydanie 6; strony 157-158, 165-166</li>
	<li>Le, D. D. i Fujimori, D. G. (2012). Enzymy metylujące białka i kwasy nukleinowe: mechanizmy i regulacja. Aktualna opinia w biologii chemicznej, 16(5-6), 507–515. doi:10.1016/j.cbpa.2012.09.014</li>
	<li>Khidekel, N., & Hsieh-Wilson, L. C. (2004). "Molekularna tablica rozdzielcza" – kowalencyjne modyfikacje białek i ich wpływ na transkrypcję. Chemia organiczna i biomolekularna, 2(1), 1-7.</li>
	<li>Maclaine, N. J. i Hupp, T. R. (2009). Regulacja p53 przez fosforylację: model pokazujący, jak różne sygnały integrują się ze szlakiem p53. Starzenie się, 1(5), 490.</li>
</ol>

kowalencyjnie połączone regulatory białek

Białka mogą ulegać wielu rodzajom modyfikacji potranslacyjnych, często w odpowiedzi na zmiany w ich środowisku. Modyfikacje te odgrywają ważną rolę w funkcjonowaniu i stabilności tych białek. Cząsteczki połączone kowalencyjnie obejmują grupy funkcyjne, takie jak grupy metylowe, acetylowe i fosforanowe, a także małe białka, takie jak ubikwityna. Zidentyfikowano około 200 różnych typów regulatorów kowalencyjnych. Grupy te modyfikują określone aminokwasy w białku. Grupy fosforanowe mogą być kowalencyjnie przyłączone tylko do aminokwasów seryny, treoniny i tyrozyny, podczas gdy grupy metylowe i acetylowe mogą być połączone tylko z lizyną. Grupy te są dodawane i usuwane z białka przez enzym lub parę enzymów. Na przykład acetylotransferaza dodaje grupę acetylową do białka, a deacetylaza może ją usunąć. Każdy z tych modyfikatorów może mieć różny wpływ na białko, do którego jest przyłączony, w zależności od liczby i lokalizacji modyfikacji. Kiedy pojedyncza cząsteczka ubikwityny jest kowalencyjnie połączona z pewnym receptorem na powierzchni komórki, białko to jest celem endocytozy; z drugiej strony, gdy do tego białka przyłączonych jest wiele połączonych ze sobą ubikwityn, jest ono oznaczane jako cel degradacji proteolitycznej. Pojedyncze białko może podlegać jednocześnie wielu modyfikacjom w celu kontrolowania jego funkcji. Dobrze znanym przykładem białka regulowanego przez wiele modyfikacji kowalencyjnych jest białko supresorowe nowotworu, p53. Ulega ono różnym modyfikacjom w odpowiedzi na różne rodzaje stresu, w tym promieniowanie i czynniki rakotwórcze. Niektóre modyfikacje obejmują fosforylację, acetylację i sumoilację w odpowiedzi na promieniowanie UV i gamma. Miejsca i rodzaje modyfikacji mogą się różnić w zależności od stresora. Badania wykazały, że promieniowanie UV i gamma może powodować fosforylację seryny 33, ale seryna 392 może ulegać fosforylacji pod wpływem promieniowania UV, ale nie gamma. Inne rodzaje stresu, takie jak narażenie na niedotlenienie, antymetabolity i aktynomycynę D, mogą powodować acetylację p53. Modyfikacje mogą się również różnić w zależności od różnych typów komórek i organizmów.

Kowalencyjnie połączone regulatory białek

Białka mogą ulegać wielu rodzajom modyfikacji potranslacyjnych, często w odpowiedzi na zmiany w ich środowisku. Te modyfikacje odgrywają ...

Education

JoVE Core

Cell Biology

Biologia komórki

Unit 1

Jednostka 1

Protein Function

Funkcja białka

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

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

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

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

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HS-LS1-2

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HS-LS1-3

Protein Regulation by Covalent Bonds

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