Name: gtpase molecular switches and control
Uploaded: 2023-04-30T18:28:43.000Z
Duration: 2 min 14 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

GTPases and their Regulation

جوانوزين ثلاثي الفوسفات جى تى بى قريب من إيه تى بى هو جزيء صغير مهم لتنظيم وظيفة البروتين. بروتينات جى هى بروتينات تُنظم بواسطة الإرتباط بجى تى بى. 00:00:15.850 00:00:19.780 هذه البروتينات لها نشاط جى تى بييز راسخ بمعنى أن عندما الجى تى بى يرتبط بها فإنها تحفز تحلله المائى لجوانوزين ثنائي الفوسفات جى تى بى.تنقسم الى فئتين الفئات الصغيرة والكبيرة. البروتينات جى الصغيرة أو بروتينات جى أحادية الوحدات, هي وحدة بروتين أحادية حيث هذا البروتين ينشط بواسطة مسارات إرسال خلوية مختلفة. وعلى العكس الكبير أو بروتينات ج الثلاثي الوحدات المتغاير, تحتوي على ثلاث وحدات فرعية ويتم تنشيطها بواسطة مستقبلات بروتين ج المقترنة بالغشاء.جى تى بيز تعمل كمحول جزيئي حيث حالة جى دى بى المرتبطة عادة تكون غير نشطة بينما حالة جى تى بى المرتبطة تكون نشطة ارتباط جى تى بى الذى يكون متبوعا بالتحلل المائى للجى تى بى الى جى دى بى, هو جزء من دورة جى تى بى جى دى بى تبدأ الدورة عندما عامل تبادل الجوانين أو جى أيه أف, يحفز تغيير توافقى فى البروتين جى جى دى بى فيتسبب بذلك في تحرير يرتبط بسرعة بمواقع ربط النوكليوتيدات الفارغة, جى تى بى حيث أن جى تى بى وفيرة فى السيتوبلازم. بروتين جى يتحول الآن الى حالته النشطة بربط جى تى بى 00:01:36.820 00:01:39.970 بروتينات جى بها نشاط جى تى بى راسخ لتحليل الجزيء المرتبط ومع ذلك فإن تكسير جى تبى بواسطة الإنزيم تكون عملية بطيئة بدون إشارات خلوية إضافية. لذلك, عندما يحين الوقت للبروتين جى ليكون غيرفعال فإن المنشط جى تى بيز أو جى إيه بى سوف يربط ويعزز نشاط الجىتى بيز للبروتين.تكسّر الى جى دى بى و فوسفات غير عضوى, جى تى بى 00:02:06.970 00:02:10.630 ويعود البروتين جى إلى حالته غير النشطة, استكمالا للدورة

<ol>
	<li>ميشرا ، إيه كي ، ولامبريت ، دي جي (2016). مراجعة مدعوة: GTPases الصغيرة ونقاط التقدم بها. البوليمرات الحيوية ، 105 (8) ، 431-448.</li>
	<li>توما فوكاي ، س. ، وشيميزو ، ت. (2019). رؤى هيكلية حول آلية تنظيم GTPases الصغيرة من قبل مرفق البيئة العالمية. الجزيئات (بازل ، سويسرا) ، 24 (18) ، 3308.</li>
</ol>

gtpases وتنظيمها

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 البروتينات المرتبطة بالنيوكليوتيدات الجوانينية (بروتينات G)، والمعروفة أيضًا باسم GTPases، هي فصيلة فائقة من البروتينات التي تنظم العديد من العمليات الخلوية، مثل إشارات الخلية، والنقل الحويصلي، وتنظيم شكل الخلية وحركتها. يمكن أن تؤدي طفرة أو خلل في هذه البروتينات إلى المرض. يوجد حوالي 40.000 بروتين G معروف يمكن تصنيفها على نطاق واسع إلى مجموعتين - بروتينات G صغيرة تتكون من مجال واحد وبروتينات G كبيرة متعددة المجالات.

تتكون بروتينات G الكبيرة، والمعروفة أيضًا باسم بروتينات G الثلاثية غير المتجانسة، من ثلاث وحدات فرعية - α و β و γ. تحتوي الوحدة الفرعية α على مجال محفوظ يتفاعل مع المستقبلات المقترنة بالبروتين G للتوسط في إشارات الغشاء

تتألف بروتينات G الصغيرة من وحدة فرعية واحدة وترسل إشارة في جميع أنحاء الخلية في مجموعة متنوعة من المسارات. وهي مقسمة إلى خمس فصائل فرعية على أساس التسلسل والوظيفة - راس، رو، راب، ران، وارف. تؤدي الطفرات في فصيلة راس إلى تكوين أورام سرطانية في الرئتين والقولون والبنكرياس. تنظم فصيلة رو إعادة تنظيم الأكتين وديناميكيات الهيكل الخلوي للأنابيب الدقيقة. تنظم فصيلة راب، وهي أكبر عائلة صغيرة من بروتين G، نقل الحويصلات ونقل الأغشية في المسارات الإفرازية والداخلية. تنظم فصيلة ران النقل نوكليوسايتوبلازمي للحمض النووي الريبي (RNA) والبروتينات من خلال المسام النووي ومجموعة المغزل الانقسامي ووظيفتها. وتشارك عائلة Arf في نقل الحويصلات والاتجار بالأغشية.

يتم تنظيم بروتينات G عن طريق ربط ثنائي فوسفات الغوانوزين/ ثلاثي فوسفات الغوانوزين (GTP/GDP) ولها نشاط GTPase جوهري، مما يعني أنها تستطيع تحلل ثلاثي فوسفات الغوانوزين إلى ثنائي فوسفات الغوانوزين (GDP)الناتج المحلي الإجمالي. عندما يرتبط ثلاثي فوسفات الغوانوزين، يكون البروتين G في حالة "ON"، أي أن البروتين سيعزز سلسلة الإشارات في الخلية. عندما يكون ثنائي فوسفات الغوانوزين (GDP)الناتج المحلي الإجمالي مقيدًا، فإنه يكون في حالة "إيقاف التشغيل"، مما يتسبب في توقف الإشارة. تنظيم تنشيط البروتين G يتم تنظيمه بشكل أكبر بواسطة عوامل تبادل نيوكليوتيدات الجوانين (GEFs)، والتي تساعد في تفكك ثنائي فوسفات الغوانوزين (GDP)الناتج المحلي الإجمالي، وبروتينات تنشيط GTPase (GAPs) التي تحفز التحلل المائي GTP. بالإضافة إلى ذلك، يمكن لمثبطات تفكك الجوانين (GDIs) الارتباط بـ GTPases الصغيرة وتنظيم موقعها في الغشاء أو السيتوبلازم.

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GTPases وتنظيمها

البروتينات المرتبطة بالنيوكليوتيدات الجوانين (بروتينات G) ، والمعروفة أيضا باسم GTPases ، هي عائلة فائقة من البروتينات التي تنظم العديد من العمليات الخلوية ، مثل الخلية ...

Education

JoVE Core

Cell Biology

بيولوجيا الخلية

Unit 1

الوحدة الأولى

Protein Function

وظيفة البروتين

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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 by other proteins as well. Some proteins help GTPases exchange GDP for GTP, while others speed up GTP breakdown. These regulators make sure GTPases respond at the right time and in the right place.

GTPase Molecular Switches and Control

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

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

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

Explore how GTPases act as molecular switches and how GTP and GDP binding, plus regulator proteins, control when they are active or inactive.

GTPase Molecular Switches and Control | JoVE K12

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Protein Complexes with Interchangeable Parts

Mechanical Protein Function

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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Homeostatic Imbalance

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HS-LS1-3

GTPase Molecular Switches and Control

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