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

Molte proteine sono regolate da molecole legate covalentemente compresi gruppi funzionali, come metile o acetile, frazioni e piccole proteine, come l'ubiquitina. Legami covalenti si verificano su specifici aminoacidi nella catena polipeptidica;ad esempio, i gruppi fosfato sono legati covalentemente a serina, treonina o tirosina. Gruppi metile e acetile sono legati alla lisina e l'ubiquitina è legata alla lisina, alla cistina, alla serina, o ai residui di treonina.Un enzima o una coppia di enzimi reversibilmente catalizza queste modifiche post-traduzionali, e l'acetil transferasi può acetilare una proteina mentre una diacetilasi può successivamente rimuovere il gruppo;queste modifiche possono alterare la funzione di una proteina o la localizzazione in una cellula. L'acetilazione delle proteine istoniche, ad esempio, regola l'espressione genica, aprendo la struttura del DNA per attivare la trascrizione genica. La metilazione delle proteine istoniche, invece, è nota per reprimere la trascrizione restringendone la struttura.Un altro esempio è il p53, un soppressore multiplo principale tumorale, proteina che subisce parecchie modifiche covalenti in risposta allo stress. L'esposizione ad agenti che danneggiano il DNA, quali raggi UV e raggi gamma può portare alla fosforilazione della proteina. La fosforilazione migliora la stabilità e attiva il p53 inducendolo a legarsi al DNA danneggiato dalla radiazione e impedisce alle cellule con DNA mutato di dividersi in modo incontrollabile.Oltre alla fosforilazione, diversi tipi di modifiche che si verificano su una singola molecola proteica, come p53, permettono di controllare con precisione le sue funzioni, come l'arresto del ciclo cellulare, 00:01 58.540-00:02:02.340 la riparazione del DNA e l'apoptosi di una cellula.

<ol>
	<li>1ID PDB: 1UBQ 
	Vijay-Kumar, S., Bugg, C.E., Cook, W.J. (1987) Struttura dell'ubiquitina raffinata a una risoluzione di 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) La banca dati delle proteine Ricerca sugli acidi nucleici, 28: 235-242.</li>
	<li>D. Sehnal, A.S. Rose, J. Kovca, S.K. Burley, S. Velankar (2018) Mol*: Verso una libreria e strumenti comuni per la grafica molecolare web MolVA/EuroVis Atti. doi:10.2312/molva.20181103</li>
	<li>Alberts et al., 6a edizione; pagine 157-158, 165-166</li>
	<li>Le, D. D., & Fujimori, D. G. (2012). Enzimi metilanti delle proteine e degli acidi nucleici: meccanismi e regolazione. Opinione attuale in biologia chimica, 16(5-6), 507–515. DOI:10.1016/j.cbpa.2012.09.014</li>
	<li>Khidekel, N., & Hsieh-Wilson, L. C. (2004). Un "centralino molecolare": modifiche covalenti alle proteine e il loro impatto sulla trascrizione. Chimica organica e biomolecolare, 2(1), 1-7.</li>
	<li>Maclaine, N. J., & Hupp, T. R. (2009). La regolazione di p53 mediante fosforilazione: un modello per come segnali distinti si integrano nella via di p53. Invecchiamento, 1(5), 490.</li>
</ol>

regolatori proteici legati covalentemente

Le proteine possono subire molti tipi di modifiche post-traduzionali, spesso in risposta a cambiamenti nel loro ambiente. Queste modifiche svolgono un ruolo importante nella funzione e nella stabilità di queste proteine. Le molecole legate in modo covalente includono gruppi funzionali, come i gruppi metile, acetile e fosfato, e anche piccole proteine, come l'ubiquitina. Sono stati identificati circa 200 tipi diversi di regolatori covalenti.

Questi gruppi modificano amminoacidi specifici in una proteina. I gruppi fosfato possono essere legati covalentemente solo agli amminoacidi serina, treonina e tirosina, mentre i gruppi metile e acetile possono essere legati solo alla lisina. Questi gruppi vengono aggiunti e rimossi da una proteina da un enzima o da una coppia di enzimi. Ad esempio, un'acetiltransferasi aggiunge un gruppo acetile a una proteina e una deacetilasi può rimuoverlo. Ciascuno di questi modificatori può avere effetti diversi sulla proteina a cui è attaccato a seconda del numero e della posizione delle modifiche. Quando una singola molecola di ubiquitina è legata covalentemente a un determinato recettore della superficie cellulare, questa proteina viene presa di mira per l'endocitosi; d'altra parte, quando più ubiquitine legate insieme sono attaccate a questa proteina, questa viene contrassegnata come bersaglio per la degradazione proteolitica.

Una singola proteina può subire più modifiche contemporaneamente per controllare la sua funzione. Un esempio ben noto di proteina regolata da molteplici modifiche covalenti è la proteina soppressore del tumore, p53. p53 subisce una serie di modifiche in risposta a vari tipi di stress, comprese le radiazioni e gli agenti cancerogeni. Alcune modifiche includono la fosforilazione, l'acetilazione e la sumoilazione in risposta alle radiazioni UV e gamma. I siti e i tipi di modifiche possono variare a seconda del fattore di stress. Gli studi hanno dimostrato che le radiazioni UV e gamma possono provocare la fosforilazione della serina 33, ma la serina 392 può essere fosforilata se esposta ai raggi UV ma non alle radiazioni gamma. Altri tipi di stress, come l’esposizione all’ipossia, agli antimetaboliti e all’actinomicina D, possono provocare l’acetilazione di p53. Le modifiche possono anche variare tra diversi tipi di cellule e organismi.

Regolatori proteici legati covalentemente

Le proteine possono subire molti tipi di modifiche post-traduzionali, spesso in risposta a cambiamenti nel loro ambiente. Queste modifiche svolgono un ruolo ...

Education

Didattica

JoVE Core

Cell Biology

Biologia cellulare

Unit 1

Unità 1

Protein Function

Funzione proteica

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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

Enzyme helpers include cofactors and coenzymes. Enzymes are proteins made of amino acids, and the functional groups on those amino acids can drive many chemical reactions through ionic interactions or acid-base reactions. But amino acids alone cannot handle oxidation-reduction and group transfer reactions, so they need non-protein helpers called cofactors. Cofactors are often described as the chemical teeth of an enzyme. They can be metal ions or organic molecules called coenzymes. These...

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 Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

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GTPases and their Regulation

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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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HS-LS1-3

Protein Regulation by Covalent Bonds

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