Name: modular protein complexes in cells
Uploaded: 2023-04-30T18:28:43.000Z
Duration: 1 min 57 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

protein-complexes-with-interchangeable-parts

Protein Complexes with Interchangeable Parts

Protein complexes are composed of multiple non-covalently linked proteins, where each component provides a different function to the complex.&#160;
One or more of these individual proteins can be replaced by closely related variants to create an alternate complex that is functionally distinct.
As an organism evolves, the gene for a beneficial protein may duplicate within the genome. This duplicated copy is free to undergo mutations without affecting the function of the original protein.&#160;
These mutations generate families of related proteins. This is one of the ways a cell can generate a protein complex containing interchangeable parts.&#160;&#160;
SCF ubiquitin ligase is a multimeric protein made of five subunits.&#160; Its function is to attach ubiquitin molecules to target proteins, marking them for degradation by proteolytic enzymes.&#160;
One of the protein&#8217;s subunits, the F-box, which is responsible for binding to the target protein has several variants that are interchangeable. A change in this subunit enables the complex to mark different proteins for degradation.&#160;
Saccharomyces cerevisiae, commonly known as baker&#8217;s yeast, has 11 variants of F-box subunits, enabling the ligase to mark proteins involved in a variety of cell processes.
For example, the cdc4 F-box protein targets cell cycle regulators, such as Sic1 and Far1, that inhibit enzymes that promote the cell cycle.&#160; Their degradation allows the cell cycle to proceed.&#160;
Variation in the F-box across organisms generates hundreds of distinct complexes with similar functions but distinct targets.

protein complexes with interchangeable parts

Groepen eiwitten kunnen een complex vormen waarbij elk eiwit in dit complex een andere rol speelt in de algehele uitvoering van de functie van het complex. Vaak kunnen sommige eiwitten in het complex worden vervangen door een nauw verwante variant, waardoor een complex ontstaat dat veel van dezelfde componenten bevat en toch functioneel verschillend is.

Het SCF-ubiquitineligase is een eiwitcomplex van vijf individuele eiwitten. Dit complex hecht ubiquitine aan andere doeleiwitten om ze te markeren voor afbraak. Om deze functie uit te voeren is een van de eiwitten, de F-box, verantwoordelijk voor binding aan het substraat, waardoor een ander eiwit in het complex, het ubiquitine-conjugerende enzym, toegang krijgt tot het substraat en ubiquitine kan hechten. Het F-box-eiwit heeft meerdere uitwisselbare varianten waardoor het complex verschillende substraten kan herkennen. Bovendien kunnen verschillende organismen verschillende sets F-box-eiwitvarianten hebben. Mensen hebben 38 bekende varianten, Saccharomyces cerevisiae heeft er 11, Drosophila heeft er 22 en C. elegans heeft er 326. Deze variatie stelt het complex in staat zich op een groot spectrum aan eiwitten te richten door slechts één van de componenten ervan te veranderen.

Deze uitwisselbare varianten zijn vaak het resultaat van genduplicatie. Tijdens moleculaire evolutie kan het gen voor een nuttig eiwit soms dupliceren tijdens DNA-replicatie vanwege redenen zoals ectopische recombinatie, replicatieslip, aneuploïdie, polyploïdie en retrotranspositie. Deze gedupliceerde kopie van het gen kan verder mutaties ondergaan terwijl deze van de ene generatie op de volgende wordt overgedragen, aangezien de mutatie de functie van het oorspronkelijke gen niet beïnvloedt. Deze mutaties resulteren in varianten van een gen dat verantwoordelijk is voor eiwitten, zoals de F-box, die functioneel vergelijkbaar zijn maar verschillende substraatspecificiteiten hebben.

Groups of proteins may form a complex where each protein in this complex has a different role in the overall execution of the complex&#8217;s function. ...

Education

JoVE Core

Cell Biology

Celbiologie

Unit 1

Eenheid 1

Protein Function

Eiwitfunctie

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Eiwitcomplexen met uitwisselbare onderdelen

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 recognize different target proteins. This lets one core complex act on many different targets.

This kind of protein complex shows how cells use shared building blocks to create functional variety. By swapping one part, the same basic structure can take on new roles in protein control.

Modular Protein Complexes in Cells

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

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

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 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 cells build protein complexes from interchangeable parts, including the SCF ubiquitin ligase and its F-box subunit that determines target specificity.

Modular Protein Complexes in Cells | 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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Homeostasis
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HS-LS1-2

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HS-LS1-3

Modular Protein Complexes in Cells

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