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

Muitas proteínas são reguladas por moléculas covalentemente ligadas, incluindo grupos funcionais, tais como metilo ou acetilo e pequenas proteínas, tais como ubiquitina. As ligações covalentes ocorrem em aminoácidos específicos na cadeia polipeptídica. Por exemplo, os grupos de fosfato são covalentemente ligados à serina, treonina, ou tirosina.Os grupos de metilo e acetilo estão ligados à lisina. A ubiquitina está ligada a lisina, cistina, serina, ou resíduos de treonina. Uma enzima ou par de enzimas reversivelmente catalisa estas modificações pós-translacionais.E a acetilo-transferase pode acetilasse uma proteína enquanto uma diacetilasse pode remover mais tarde o grupo. Estas modificações podem alterar a função de uma proteína ou a localização em uma célula. Por exemplo, a acetilação de proteínas histonas regula a expressão gênica abrindo a estrutura de DNA para ativar a transcrição gênica.A metilação de proteínas histonas, por outro lado, é conhecida para reprimir a transcrição apertando a estrutura. Outro exemplo é p53, uma proteína supressora tumoral principal múltipla que sofre diversas modificações covalentes em resposta ao estresse. A exposição aos agentes prejudiciais do DNA, tais como a radiação UV e gama pode resultar na fosforilação da proteína.A fosforilação melhora a estabilidade e ativa p53 fazendo com que ele se ligue ao DNA danificado pela radiação e impeça células com DNA mutado de dividir incontrolavelmente. Além da fosforilação, Diferentes tipos de modificações ocorrem em uma única molécula de proteína, que tal como p53, permitem que ela controle precisamente suas funções, tais como ciclo de células, reparo de DNA e apoptose de uma célula.

<ol>
	<li>1ID do PDB: 1UBQ 
	Vijay-Kumar, S., Bugg, CE, Cook, WJ (1987) Estrutura da ubiquitina refinada em resolução de 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) A Pesquisa de Ácidos Nucleicos do Banco de Dados de Proteínas, 28: 235-242.</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol*: Rumo a uma biblioteca comum e ferramentas para gráficos moleculares da web MolVA/EuroVis Proceedings. doi:10.2312/molva.20181103</li>
	<li>Alberts et al., 6ª edição; páginas 157-158, 165-166</li>
	<li>Le, DD, & Fujimori, DG (2012). Enzimas metilantes de proteínas e ácidos nucleicos: mecanismos e regulação. Opinião atual em biologia química, 16(5-6), 507–515. DOI:10.1016/j.cbpa.2012.09.014</li>
	<li>Khidekel, N., & Hsieh-Wilson, L. C. (2004). Um 'quadro de distribuição molecular' - modificações covalentes nas proteínas e seu impacto na transcrição. Química orgânica e biomolecular, 2 (1), 1-7.</li>
	<li>Maclaine, N. J., & Hupp, T. R. (2009). A regulação do p53 por fosforilação: um modelo de como sinais distintos se integram à via do p53. Envelhecimento, 1(5), 490.</li>
</ol>

reguladores de proteínas ligadas covalentemente

As proteínas podem sofrer muitos tipos de modificações pós-traducionais, muitas vezes em resposta a mudanças no seu ambiente. Estas modificações desempenham um papel importante na função e estabilidade destas proteínas. Moléculas ligadas covalentemente incluem grupos funcionais, como grupos metil, acetil e fosfato, e também pequenas proteínas, como a ubiquitina. Existem cerca de 200 tipos diferentes de reguladores covalentes que foram identificados. Esses grupos modificam aminoácidos específicos em uma proteína. Os grupos fosfato só podem ser ligados covalentemente aos aminoácidos serina, treonina e tirosina, enquanto os grupos metil e acetil só podem ser ligados à lisina. Esses grupos são adicionados e removidos de uma proteína por uma enzima ou par de enzimas. Por exemplo, uma acetiltransferase adiciona um grupo acetil a uma proteína e uma desacetilase pode removê-lo. Cada um desses modificadores pode ter efeitos diferentes na proteína à qual está ligado, dependendo do número e da localização das modificações. Quando uma única molécula de ubiquitina está covalentemente ligada a um determinado receptor da superfície celular, esta proteína é alvo de endocitose; por outro lado, quando múltiplas ubiquitinas ligadas entre si estão ligadas a esta proteína, ela é marcada como alvo para degradação proteolítica. Uma única proteína pode sofrer múltiplas modificações simultaneamente para controlar sua função. Um exemplo bem conhecido de uma proteína regulada por múltiplas modificações covalentes é a proteína supressora de tumor, p53. A p53 sofre uma variedade de modificações em resposta a vários tipos de estresse, incluindo radiação e agentes cancerígenos. Algumas modificações incluem fosforilação, acetilação e sumoilação em resposta às radiações UV e gama. Os locais e tipos de modificações podem variar dependendo do estressor. Estudos demonstraram que a radiação UV e gama pode resultar na fosforilação da serina 33, mas a serina 392 pode ser fosforilada quando exposta à radiação UV, mas não à radiação gama. Outros tipos de estresse, como a exposição à hipóxia, antimetabólitos e actinomicina D, podem resultar na acetilação da p53. As modificações também podem variar entre diferentes tipos de células e organismos.

Reguladores de Proteínas Ligadas Covalentemente

As proteínas podem sofrer muitos tipos de modificações pós-traducionais, muitas vezes em resposta a mudanças em seu ambiente. Essas modificações desempenham um ...

Education

JoVE Core

Cell Biology

Biologia Celular

Unit 1

Unidade 1

Protein Function

Função Proteica

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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

cell biology

JoVE Core - Biologia Celular ilustra processos celulares complexos em vídeos de animação fáceis de entender e, ao mesmo tempo, abrangentes. Esta coleção foca nos componentes e funções essenciais das células, incluindo organelas e membranas, transporte celular e energia celular. É complementado por vídeos de Cientistas em ação que demonstram a aplicação da biologia celular em experimentos de pesquisa do mundo real.

Characteristics of Life

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GTPases and their Regulation

Protein Complexes with Interchangeable Parts

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Structural Protein Function

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Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. [Assessment Boundary: Assessment does not include identification of specific cell or tissue types, whole body systems, specific protein structures and functions, or the biochemistry of protein synthesis.]

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Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. [Clarification Statement: Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, and organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.] [Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction level.]

HS-LS1-2

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Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis. [Clarification Statement: Examples of investigations could include heart rate response to exercise, stomate response to moisture and temperature, and root development in response to water levels.] [Assessment Boundary: Assessment does not include the cellular processes involved in the feedback mechanism.]

HS-LS1-3

Protein Regulation by Covalent Bonds

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