Name: phosphorylation and protein control
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 1 min 2 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Life Science

LS.4

LS.4.b

Phosphorylation

זרחון, ההוספה של קבוצת פוספט, הוא שינוי חשוב עבור תאים כדי לווסת את תפקוד חלבונים. כאשר מסירים קבוצה פוספט במהלך הידרוליזה של ATP, אנזימים הנקראים פרוטאין קינאז יכולים לזרז את הקישור הקוולנטי של קבוצה זו לשרשראות צדדיות של חומצת אמינו מסוימת בחלבון. כתוצאה מכך, החלבון משנה צורה או מאפשר לחלבונים אחרים להצמד לאזורים שעברו זרחון.שינויים אלה יכולים לשנות את תפקוד החלבון ואולי אף להפעיל או לנטרל אותו לחלוטין. ניתן להסיר את קבוצת הפוספט על-ידי פעילות פרוטאין פוספטאז, אנזימים המזרזים את ביטול הזרחון בחלבונים, ו‫למעשה הופכים את התגובה. על-ידי ויסות זרחון בדרך זו, הפעילות של חלבונים מסוימים ניתנת לשפעול, הפסקה או שינוי הפיכים, בהתאם לנדרש בתא.

קיריאקיס, ג'ון מ. "בהתחלה, היה זרחן חלבון." כתב העת לכימיה ביולוגית 289, מס '14 (אפריל 4, 2014): 9460-62. [<a href="https://doi.org/10.1074/jbc.R114.557926" target="__blank">מקור</a>]
ארדיטו, פטימה, מיקלה ג'וליאני, דונטלה פרונה, ג'וזפה טרויאנו ולורנצו לו מוציו. "התפקיד המכריע של זרחן חלבון באיתות התא והשימוש בו כטיפול ממוקד (סקירה)." International Journal of Molecular Medicine 40, no. 2 (אוגוסט 2017): 271–80. [<a href="https://doi.org/10.3892/ijmm.2017.3036" target="__blank">מקור</a>]

זרחון

<div style="direction:rtl">הוספה או הסרה של קבוצות פוספט מחלבונים היא השינוי הכימי הנפוץ ביותר המווסת תהליכים תאיים. שינויים אלה יכולים להשפיע על המבנה, הפעילות, היציבות והלוקליזציה של חלבונים בתוך תאים, כמו גם על האינטראקציות שלהם עם חלבונים אחרים. במהלך זרחון, חלבונים קינאזות מעבירות את קבוצת הפוספט הסופי של ATP לשרשראות צד ספציפיות של חומצות אמינו של חלבוני המצע. סרין, תרונין וטירוזין הן חומצות האמינו הפוספורילציות הנפוצות ביותר. בהתאם לכך, קינאזות חלבון מסווגות כקנאזות סרין/תרונין, קינאזות טירוזין או קינאזות עם פעולה כפולה אם הן יכולות לזרחן את כל שלוש חומצות האמינו. לעומת זאת, פוספטזות חלבון מזרזות את הסרת קבוצת הפוספט (דה-פוספורילציה), ומשחזרות את התכונות המקוריות של החלבון. בתנאים פיזיולוגיים, זרחון ודפוספורילציה מוסדרים היטב כדי למנוע שינויים ממושכים במבנה ובתפקוד החלבון. הפרעה באיזון זה עלולה לגרום למחלות, לרבות סרטן והפרעות ניווניות שונות. לדוגמה, חלבון בשם טאו עובר זרחון יתר במחלת אלצהיימר (AD). מבחינה פיזיולוגית, טאו מווסת את הצורה, המבנה וההתפתחות של נוירונים. חלבון הטאו מכיל למעלה מ-80 שאריות של סרין, תראונין וטירוזין, שרק חלק מהם בדרך כלל מזורחן. במוחם של חולים עם AD, הטאו מזורחן בצורה חריגה ומוגזמת. זה משנה את מסיסות החלבון, ויוצר אגרגטים רעילים בלתי מסיסים המובילים למוות נוירוני.</div>

הוספה או הסרה של קבוצות פוספטים מחלבונים היא השינוי הכימי הנפוץ ביותר המווסת תהליכים תאיים. שינויים אלה ...

Education

JoVE Core

Biology

ביולוגיה

Cellular Processes

תהליכים תאיים

Metabolism

חילוף חומרים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

phosphorylation and protein control

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins.

During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often phosphorylated are serine, threonine, and tyrosine. Protein kinases are grouped as serine/threonine kinases, tyrosine kinases, or dual action kinases when they can phosphorylate all three.

Protein phosphatases carry out the reverse step. They remove the phosphate group in a process called dephosphorylation, which restores the protein’s original properties. In healthy cells, phosphorylation and dephosphorylation are carefully balanced so protein shape and function do not stay changed for too long.

When this balance is disrupted, disease can result. Examples include cancer and several neurodegenerative disorders. Tau is one important example. In healthy neurons, tau helps regulate neuron shape, structure, and development. Tau has more than 80 serine, threonine, and tyrosine sites, but only some are normally phosphorylated. In Alzheimer’s disease, tau becomes hyperphosphorylated, or abnormally over-phosphorylated. This makes the protein less soluble and leads to toxic insoluble aggregates that contribute to neuronal death.

Phosphorylation and Protein Control

what is metabolism?

Metabolism, Energy, and Cell Reactions

Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

first law of thermodynamics

Energy Flow in a Food Web

Energy flow in a food web shows the First Law of Thermodynamics in action. Energy cannot be created or destroyed. It can only change form as it moves through living things and the environment. Sunlight is the starting point. Plants capture radiant energy from the sun during photosynthesis and turn it into chemical energy stored in complex carbohydrates. At the same time, oxygen is released into the atmosphere. Herbivores eat the plants and use those sugars during digestion. The energy is...

second law of thermodynamics

Entropy in Food Web Energy Flow

The Second Law of Thermodynamics explains why entropy increases as energy moves through a system. Entropy means the amount of disorder in a system. Each time energy is transferred or transformed, some energy is lost as unusable heat. That heat can raise the motion of nearby molecules for a short time and make the surroundings less ordered and more random. This idea also appears in a food web. Primary producers, such as plants, take in energy from the sun and make food. During this process,...

kinetic energy

Motion as a Source of Energy

Kinetic energy is the energy of motion. It appears when an object is moving and can do work or cause change. A waterfall is one clear example. Water behind a dam has potential energy, but when it rushes downward, that moving water has kinetic energy. When the water reaches the bottom and stops moving, its energy can become potential energy again. Kinetic energy also shows up in living systems. Plants absorb light particles, called photons, which move very fast and help create chemical energy...

potential energy

Stored Energy in Motion and Bonds

Stored energy in motion and bonds is called potential energy. It depends on the structure of an object or the position of matter in space. Raising a kettlebell changes its location and increases its potential energy. A stretched rubber band also stores potential energy, which can later change into kinetic energy. Chemical bonds between atoms hold another form of stored energy called chemical energy. These bonds involve attractive forces, and that energy can change into other forms during a...

free energy

Gibbs Free Energy in Chemical Reactions

Gibbs free energy is a measure of useful energy that can be taken from a chemical reaction to do work. It is written as G and named for scientist Gibbs, who discovered it. This energy is what remains after entropy is considered. A reaction can either take in energy or release it. Reactions that absorb energy are called endergonic reactions. Reactions that release energy are called exergonic reactions. The direction of energy flow helps show which type of reaction is happening. Plants carry...

activation energy

How Catalysts Lower Reaction Barriers

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often. As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is...

hydrolysis of atp

ATP Breakdown and Energy Release

ATP breakdown releases energy for cell work. Adenosine triphosphate, or ATP, can lose one or two phosphate groups when water is added. This hydrolysis reaction is exergonic, which means it releases energy that the cell can use. When one phosphate group is removed, ATP becomes ADP, or adenosine diphosphate. Inorganic phosphate is also released. ADP can then be hydrolyzed again to form AMP, or adenosine monophosphate, after a second phosphate group is removed. ATP has a clear structure. It is...

phosphorylation

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

induced-fit model

How Enzymes Adjust to Their Substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products. Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical...

enzyme kinetics

Substrate Effects on Enzyme Rates

Enzyme kinetics examines how enzymes change the rate of a reaction. Enzymes speed reactions by lowering the activation energy of the reactants. The reaction rate is the speed at which an enzyme turns reactants into products, and it can be affected by several factors, including the number of available reactants. Scientists often study enzyme kinetics in a test tube with a fixed amount of enzyme. When more substrate, or reactant, is added, the reaction rate increases because the enzyme can make...

enzyme inhibition

Competitive vs Noncompetitive Inhibitors

Enzyme inhibitors are molecules that reduce enzyme activity by binding to enzymes. Cells use these inhibitors to help regulate normal enzyme function. Drugs and toxins can also block enzymes and change how they work. Some inhibitors bind at the active site, which is the part of the enzyme where the substrate normally fits. Competitive inhibitors do this by occupying the active site and preventing the substrate from binding. If the substrate concentration becomes high enough, it can outcompete...

feedback inhibition

How Cells Control Product Buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products. If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important...

allosteric regulation

Allosteric Control of Enzyme Speed

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity. Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's...

cofactors and coenzymes

Enzyme Helpers: Metals, Vitamins, and More

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

Learn how kinases add phosphate groups, phosphatases remove them, and why balanced phosphorylation matters for cell function and diseases like Alzheimer’s.

Phosphorylation and Protein Control | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

myJoVE Corporation

What is Photosynthesis?

Photosynthesis is a multipart, biochemical process that occurs in plants as well as in some bacteria. It captures carbon dioxide and solar energy to ...

Light as Energy

The energy required to carry out photosynthesis is light&#8212; typically electromagnetic radiation from the sun. The range of all possible wavelengths is ...

Anatomy of Chloroplasts

Green algae and plants, including green stems and unripe fruit, harbor chloroplasts&mdash;the vital organelles where photosynthesis takes place. In ...

Photosystem II

The multi-protein complex photosystem II (PS II) harvests photons and transfers their energy through its bound pigments to its reaction center, and ...

Photosystem I

Although structurally similar to photosystem II (PSII), photosystem I (PSI) is has a different electron supplier and electron acceptor.
Both these ...

The Calvin Cycle

Overview

Oxygenic photosynthesis converts approximately 200 billion tons of carbon dioxide (CO2) annually to organic compounds and produces approximately ...

C4 Pathway and CAM

Most plants use the C3 pathway for carbon fixation. However, some plants, such as sugar cane, corn, and cacti that grow in hot conditions, use alternative ...

Primary Production

The total amount of energy acquired by primary producers in an ecosystem is called gross primary production (GPP). However, of this energy, producers use ...

The student will investigate and understand that there are chemical processes of energy transfer which are important for life. Key ideas include photosynthesis is the foundation of virtually all food webs; and

LS.4.a

Introduction to Cellular Respiration

Organisms harvest energy from food, but this energy cannot be directly used by cells. Cells convert the energy stored in nutrients into a more usable ...

What is Glycolysis?

Overview
Cells make energy by breaking down macromolecules. Cellular respiration is the biochemical process that converts &#34;food energy&#34; (from the ...

Energy-requiring Steps of Glycolysis

Glucose is the source of nearly all energy used by organisms. The first step of converting glucose into usable energy is called glycolysis. Glycolysis ...

Energy-releasing Steps of Glycolysis

Glycolysis is divided into two phases based on whether energy is utilized or released. While the first phase consumes ATP, the second phase produces ...

Outcomes of Glycolysis

Nearly all the energy used by cells comes from the bonds that make up complex organic compounds. These organic compounds are broken down into simpler ...

Pyruvate Oxidation

After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure ...

The Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle or TCA cycle, consists of several energy-generating reactions that yield one ATP molecule, three NADH ...

Products of the Citric Acid Cycle

The cells of most organisms&#8212;including plants and animals&#8212;obtain usable energy through aerobic respiration, the oxygen-requiring version of ...

Electron Transport Chains

The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The ...

Chemiosmosis

Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives ...

Electron Carriers

Electron carriers can be thought of as electron shuttles. These compounds can easily accept electrons (i.e., be reduced) or lose them (i.e., be oxidized). ...

ATP Yield

Cellular respiration produces 30 - 32 ATP per glucose molecule. Although most of the ATP results from oxidative phosphorylation and the electron transport ...

Fermentation

Most eukaryotic organisms require oxygen to survive and function adequately. Such organisms produce large amounts of energy during aerobic respiration by ...

What is Metabolism?

Overview

Metabolism represents all of the chemical activity in a cell, including reactions that build molecules (anabolism) and those that break ...

Free Energy

Free energy&mdash;abbreviated as G for the scientist Gibbs who discovered it&mdash;is a measurement of useful energy that can be extracted from a reaction ...

Hydrolysis of ATP

The bonds of adenosine triphosphate (ATP) can be broken through the addition of water, releasing one or two phosphate groups in an exergonic process ...

The addition or removal of phosphate groups from proteins is the most common chemical modification that regulates cellular processes. These modifications ...

The student will investigate and understand that there are chemical processes of energy transfer which are important for life. Key ideas include photosynthesis and cellular respiration support life processes.

Phosphorylation and Protein Control

Description

Transcript

Tags

More videos by Standards