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

ATP'nin yakın akrabası olan Guanozin trifosfat protein işlevinin düzenlenmesi için önemli olan küçük bir moleküldür. G proteinleri, GTP bağlanması ile regüle edilen proteinlerdir. Bu proteinler, içsel GTPaz aktivitesine sahiptir.Yani, GTP bağlandığında, onun guanozin difosfat'a hidrolizini katalize edebilirler. G proteinleri, küçük ve büyük olmak üzere iki kategoriye ayrılır. Küçük veya monomerik G proteinleri, tek bir protein alt biriminden ibarettir ve çeşitli hücre içi sinyal yolları tarafından etkinleştirilir.Buna karşılık, büyük veya heterotrimerik G proteinleri, üç alt birim içerir ve membranla bağlı, G proteini ile kenetli reseptörler tarafından etkinleştirilir. GTPaz'lar, GDP-bağlı durum genellikle etkin değilken, ancak GTP-bağlı durum etkinken, bir moleküler anahtar görevi görür. GTP ile bağlanma ve ardından GTP'den GDP'ye hidroliz, GDP GTP döngüsünün bir parçasıdır.Döngü, bir guanin değişim faktörü G proteininde GDP'nin serbest bırakılmasını sağlayan yapısal bir değişikliğe neden olduğunda başlar. GTP, sitoplazmada bol miktarda bulunduğundan, kısa sürede boş kalan nükleotid bağlanma yerine bağlanır. G proteini artık GTP bağlı olarak, aktif durumuna geçmiştir.G proteinleri, bağlı molekülü hidrolize etmek için içsel GTPaz aktivitesine sahiptir. Bununla birlikte, enzim tarafından GTP'nin yıkımı, ek hücresel sinyaller olmadan yavaş bir işlemdir. Bu nedenle, G proteininin kapatılma zamanı geldiğinde, bir GTPaz etkinleştirici protein bağlanır ve proteinin GTPaz aktivitesini yükseltir.GTP, GDP ve inorganik fosfata ayrılır ve G proteini aktif olmayan durumuna geri dönerek döngüyü tamamlar.

<ol>
	<li>Mishra, A. K. ve Lambright, D. G. (2016). Davetli inceleme: Küçük GTPazlar ve GAP'leri. Biyopolimerler, 105(8), 431–448.</li>
	<li>Toma-Fukai, S. ve Shimizu, T. (2019). GEF'ler tarafından Küçük GTPazların Düzenleme Mekanizmasına İlişkin Yapısal Bilgiler. Moleküller (Basel, İsviçre), 24(18), 3308.</li>
</ol>

gtpazlar ve yönetmelikleri

GTPazlar olarak da bilinen guanin nükleotid bağlayıcı proteinler (G-proteinler), hücre sinyallemesi, veziküler taşınma ve hücre şekli ve hareketliliğinin düzenlenmesi gibi birçok hücresel süreci düzenleyen bir protein üst ailesidir. Bu proteinlerin mutasyonu veya işlev bozukluğu hastalığa yol açabilir. Genel olarak iki gruba ayrılabilen yaklaşık 40.000 bilinen G-proteini vardır: tek bir alandan oluşan küçük G-proteinleri ve büyük, çok alanlı G-proteinleri. Heterotrimerik G proteinleri olarak da bilinen büyük G proteinleri üç alt birimden oluşur: a, β ve y. α alt birimi, transmembran sinyallemesine aracılık etmek için G-proteinine bağlı reseptörlerle etkileşime giren korunmuş bir alana sahiptir. Küçük G proteinleri tek bir alt birimdir ve hücre boyunca çeşitli yollardan sinyal verir. Sıra ve işleve göre beş alt aileye ayrılırlar: Ras, Rho, Rab, Ran ve Arf. Ras alt ailesindeki mutasyonlar akciğerlerde, kalın bağırsakta ve pankreasta kanserli tümörlerin oluşumuna yol açar. Rho alt ailesi, yeniden aktin organizasyonunu ve mikrotübül hücre iskeleti dinamiklerini düzenler. Küçük G-protein ailelerinin en büyüğü olan Rab alt ailesi, salgı ve endositik yollarda vezikül taşınmasını ve membran trafiğini düzenler. Ran alt ailesi, nükleer gözenek ve mitotik iğ düzeneği ve işlevi yoluyla RNA ve proteinlerin nükleositoplazmik taşınmasını düzenler. Arf alt ailesi vezikül taşınması ve membran yer değiştirmesiyle ilgilidir. G-proteinleri GTP/GDP bağlanmasıyla düzenlenir ve içsel GTPaz aktivitesine sahiptir, yani GTP'yi GDP'ye hidrolize edebilirler. GTP bağlandığında, G-proteini "AÇIK" durumdadır, yani protein hücredeki sinyal basamaklarını teşvik edecektir. GDP bağlandığında "KAPALI" durumdadır ve sinyallemenin durmasına neden olur. G-protein aktivasyonunun düzenlenmesi, GDP ayrışmasına yardımcı olan guanin nükleotid değişim faktörleri (GEF'ler) ve GTP hidrolizini uyaran GTPaz aktive edici proteinler (GAP'ler) tarafından ayrıca düzenlenir. Ek olarak, guanin ayrışma inhibitörleri (GDI'ler) küçük GTPazlara bağlanabilir ve bunların membran veya sitoplazmadaki konumlarını düzenleyebilir.

GTPazlar ve Yönetmelikleri

GTPazlar olarak da bilinen guanin nükleotid bağlayıcı proteinler (G-proteinleri), hücre hücreleri gibi birçok hücresel süreci düzenleyen bir protein süper ailesidir.

Education

JoVE Core

Cell Biology

Hücre Biyolojisi

Unit 1

Ünite 1

Protein Function

Protein Fonksiyonu

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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

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

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

cell biology

JoVE Core Hücre Biyolojisi, anlaşılması kolay ancak kapsamlı animasyonlu video derslerde karmaşık hücresel süreçleri gösterir. Bu koleksiyon, organeller ve zarlar, hücresel taşıma ve hücre enerjileri dahil olmak üzere hücrelerin temel bileşenlerine ve işlevlerine odaklanır. Gerçek dünya araştırma deneylerinde hücre biyolojisinin uygulanmasını gösteren bilim insanı eylem videoları ile tamamlanmaktadır.

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Protein Complexes with Interchangeable Parts

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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

GTPase Molecular Switches and Control

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