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

Muchas proteínas están reguladas por moléculas enlazadas covalentemente, incluidos grupos funcionales, como las fracciones de metilo o acetilo, y proteínas pequeñas, como la ubiquitina.
Los enlaces covalentes se producen en aminoácidos específicos de la cadena polipeptídica. Por ejemplo, los grupos fosfato se unen covalentemente a la serina, la treonina o la tirosina; Los grupos metilo y acetilo están unidos a la lisina; y la ubiquitina está ligada a los residuos de lisina, cisteína, serina o treonina.
Una enzima o un par de enzimas cataliza de forma reversible estas modificaciones postraduccionales: una acetiltransferasa puede acetilar una proteína, mientras que una desacetilasa puede eliminar posteriormente el grupo.
Estas modificaciones pueden alterar la función o localización de una proteína en una célula.
Por ejemplo, la acetilación de las proteínas histonas regula la expresión génica al abrir la estructura del ADN para activar la transcripción génica. Por otro lado, se sabe que la metilación de las proteínas histonas reprime la transcripción al endurecer la estructura. 
Otro ejemplo es p53, una proteína supresora de tumores multidominio que sufre varias modificaciones covalentes en respuesta al estrés. La exposición a agentes que dañan el ADN, como la radiación UV y gamma, puede dar lugar a la fosforilación de la proteína. 
La fosforilación mejora la estabilidad y activa p53, haciendo que se una al ADN dañado por la radiación y evite que las células con ADN mutado se dividan sin control.
Además de la fosforilación, los diferentes tipos de modificaciones que ocurren en una sola molécula de proteína, como p53, le permiten controlar con precisión sus funciones, como la detención del ciclo celular, la reparación del ADN y la apoptosis de una célula.

<ol>
	<li>1ID de PDB: 1UBQ 
	Vijay-Kumar, S., Bugg, C.E., Cook, W.J. (1987) Estructura de la ubiquitina refinada a una resolución 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) Investigación de ácidos nucleicos del banco de datos de proteínas, 28: 235-242.</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol*: Towards a common library and tools for web molecular graphics MolVA/EuroVis Proceedings. doi:10.2312/molva.20181103</li>
	<li>Alberts et al., 6ª edición; páginas 157-158, 165-166</li>
	<li>Le, D. D., & Fujimori, D. G. (2012). Enzimas metilantes de proteínas y ácidos nucleicos: mecanismos y regulación. Opinión actual en biología química, 16(5-6), 507–515. doi:10.1016/j.cbpa.2012.09.014</li>
	<li>Khidekel, N., & Hsieh-Wilson, L. C. (2004). Un 'tablero de distribución molecular': modificaciones covalentes de proteínas y su impacto en la transcripción. Química orgánica y biomolecular, 2(1), 1-7.</li>
	<li>Maclaine, N. J., & Hupp, T. R. (2009). La regulación de p53 por fosforilación: un modelo de cómo se integran distintas señales en la vía de p53. Envejecimiento, 1(5), 490.</li>
</ol>

reguladores de proteínas unidos covalentemente

Las proteínas pueden sufrir muchos tipos de modificaciones postraduccionales, a menudo en respuesta a cambios en su entorno. Estas modificaciones juegan un papel importante en la función y estabilidad de estas proteínas. Las moléculas unidas covalentemente incluyen grupos funcionales, como los grupos metilo, acetilo y fosfato, y también proteínas pequeñas, como la ubiquitina. Se han identificado alrededor de 200 tipos diferentes de reguladores covalentes.

Estos grupos modifican aminoácidos específicos en una proteína. Los grupos fosfato sólo pueden unirse covalentemente a los aminoácidos serina, treonina y tirosina, mientras que los grupos metilo y acetilo sólo pueden unirse a la lisina. Estos grupos se añaden y eliminan de una proteína mediante una enzima o un par de enzimas. Por ejemplo, una acetiltransferasa añade un grupo acetilo a una proteína y una desacetilasa puede eliminarlo. Cada uno de estos modificadores puede tener diferentes efectos sobre la proteína a la que está unido dependiendo del número y ubicación de las modificaciones. Cuando una sola molécula de ubiquitina se une covalentemente a un determinado receptor de la superficie celular, esta proteína se dirige a la endocitosis; por otro lado, cuando se unen múltiples ubiquitinas unidas entre sí a esta proteína, se marca como un objetivo para la degradación proteolítica.

Una sola proteína puede sufrir múltiples modificaciones simultáneamente para controlar su función. Un ejemplo bien conocido de una proteína regulada por múltiples modificaciones covalentes es la proteína supresora de tumores, p53. p53 sufre una variedad de modificaciones en respuesta a varios tipos de estrés, incluida la radiación y los carcinógenos. Algunas modificaciones incluyen fosforilación, acetilación y sumoilación en respuesta a las radiaciones UV y gamma. Los sitios y tipos de modificaciones pueden variar según el factor estresante. Los estudios han demostrado que la radiación ultravioleta y gamma puede provocar la fosforilación de la serina 33, pero la serina 392 puede fosforilarse cuando se expone a la radiación ultravioleta pero no a la radiación gamma. Otros tipos de estrés, como la exposición a la hipoxia, los antimetabolitos y la actinomicina D, pueden provocar la acetilación de p53. Las modificaciones también pueden variar entre diferentes tipos de células y organismos.

Reguladores de proteínas unidos covalentemente

Las proteínas pueden sufrir muchos tipos de modificaciones postraduccionales, a menudo en respuesta a cambios en su entorno. Estas modificaciones juegan un papel ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Protein Function

Función proteica

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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

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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

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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

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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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