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

الفسفرة إضافة مجموعة الفوسفات هو تعديل مهم للخلايا لتنظيم وظيفة البروتين. عندما تتم إزالة مجموعة الفوسفات أثناء التحلل ATP الانزيمات استدعاء كيناز البروتين يمكن أن تحفز الرابطة التساهمية لهذه المجموعة لبعض السلاسل الجانبية للحمض الأميني في البروتين. نتيجة لذلك يغير البروتين الشكل أو يسمح البروتينات الأخرى لربط المناطق الفسفورية.هذه التغييرات يمكن أن تعدل وظيفة البروتين وربما حتى تنشيطه أو إلغاء تنشيطه بالكامل. يمكن إزالة مجموعة الفوسفات عن طريق عمل فسفاتاز البروتين الانزيمات التي تحفز على نزع الفسفرة من البروتينات عكس رد الفعل أساسا. من خلال تنظيم الفسفرة بهذه الطريقة نشاط بعض البروتينات يمكن تشغيل عكسها على قبالة أو تعديلها حسب الحاجة في الخلية.

كيرياكيس ، جون م. "في البداية ، كان هناك فسفرة بروتينية". مجلة الكيمياء البيولوجية 289 ، العدد 14 (4 أبريل 2014): 9460-62. [<a href = "https://doi.org/10.1074/jbc.R114.557926" target = "__blank" >المصدر</a>]
أرديتو ، فاطمة ، ميشيل جولياني ، دوناتيلا بيروني ، جوزيبي ترويانو ، ولورينزو لو موزيو. "الدور الحاسم لفسفرة البروتين في إشارات الخلية واستخدامها كعلاج موجه (مراجعة)." المجلة الدولية للطب الجزيئي 40 ، العدد 2 (أغسطس 2017): 271-80. [<a href = "https://doi.org/10.3892/ijmm.2017.3036" target = "__blank" >مصدر</a>]

الفسفرة

تعد إضافة أو إزالة مجموعات الفوسفات من البروتينات أكثر التعديلات الكيميائية شيوعاً و التي تنظم العمليات الخلوية. يمكن أن تؤثر هذه التعديلات على بنية ونشاط واستقرار وتوطين البروتينات داخل الخلايا بالإضافة إلى تفاعلاتها مع البروتينات الأخرى. 

أثناء عملية الفسفرة ، تنقل كينازات البروتين مجموعة الفوسفات الطرفية من الأدينوسين ثلاثي الفوسفات إلى سلاسل جانبية معينة من الأحماض الأمينية من بروتينات الركيزة. سيرين ، ثريونين ، وتيروزين هي الأحماض الأمينية الفسفورية الأكثر شيوعاً. وفقاً لذلك ، يتم تصنيف كينازات البروتين على أنها كينازات سيرين / ثريونين ، أو كينازات التيروزين ، أو كينازات مزدوجة الفعل إذا كان بإمكانها فسفرة جميع الأحماض الأمينية الثلاثة. على العكس من ذلك ، يحفز فوسفاتيز البروتين إزالة مجموعة الفوسفات (نزع الفسفرة) ، واستعادة الخصائص الأصلية للبروتين.

في ظل الظروف الفسيولوجية ، يتم تنظيم الفسفرة وإزالة الفسفرة بإحكام لمنع التغيرات المطولة في بنية البروتين و وظيفته. يمكن أن يؤدي اختلال هذا التوازن إلى أمراض ، بما في ذلك السرطان والاضطرابات التنكسية العصبية المختلفة. على سبيل المثال ، بروتين يسمى تاو مفرط الفسفرة في مرض الزهايمر (AD). من الناحية الفسيولوجية ، ينظم تاو شكل الخلايا العصبية وهيكلها وتطورها. يحتوي بروتين تاو على أكثر من ٨٠ بقايا سيرين وثريونين وتيروزين ، والتي عادةً ما يتم فسفرة جزء بسيط منها. في أدمغة المرضى المصابين بمرض الزهايمر ، يتم فسفرة تاو بشكل غير طبيعي ومفرط. هذا يغير قابلية ذوبان البروتين ، مكوناً تكتلات سامة غير قابلة للذوبان تؤدي إلى موت الخلايا العصبية.

تعد إضافة أو إزالة مجموعات الفوسفات من البروتينات هو التعديل الكيميائي الأكثر شيوعا الذي ينظم العمليات الخلوية. هذه التعديلات ...

Education

JoVE Core

Biology

علم الأحياء

Cellular Processes

العمليات الخلوية

Metabolism

عملية التمثيل الغذائي (الأيض)

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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

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first law of thermodynamics

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second law of thermodynamics

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kinetic energy

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potential energy

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free energy

Gibbs Free Energy in Chemical Reactions

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activation energy

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hydrolysis of atp

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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

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feedback inhibition

How Cells Control Product Buildup

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allosteric regulation

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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

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Phosphorylation and Protein Control

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