Name: protein complex formation and function
Uploaded: 2023-04-30T18:28:42.000Z
Duration: 2 min 41 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 Complex Assembly

Most proteins do not function as fully extended polypeptide chains but assemble into compact multicomponent complexes. During assembly, the growing complex must distinguish its specific components from a mixture of hundreds of different protein and non-protein species present in the cell.&#160;
Protein complexes can be either homomeric, consisting of several copies of the same polypeptide chain, or heteromeric, composed of multiple distinct polypeptide chains or non-protein components.
Usually, proteins have all the necessary information to self-assemble into functional complexes from their constituents with speed and precision.&#160;
Many viruses can self-assemble to form a fully functional unit using the infected host cell to produce all of the necessary components.
For instance, in the tobacco mosaic virus, coat protein subunits self-assemble into individual rings, in vitro. An RNA molecule binds in the center of the growing helix to make the active virus.&#160;&#160;
However, in some protein complexes, self-assembly is only due to mutation or disease.&#160;
Hemoglobin, the oxygen-carrying protein found in red blood cells, is a tetramer of two alpha subunits and two similar beta subunits. However, in sickle cell anemia, mutant hemoglobin has a hydrophobic patch that increases the affinity between hemoglobin tetramers, causing them to aggregate into an abnormal assembly of hemoglobin fibers.
These fibers change the blood cells from a spheroid to a crescent shape, thereby clogging the blood vessels.&#160;&#160;
Although many proteins self-assemble without external help, assembly factors such as molecular chaperones assist protein components to assemble into a stable and functional complex.
The 26S proteasome, molecular machinery that assists in regulated protein degradation, consists of two distinct sub-complexes: a barrel-shaped 20S core particle and two 19S regulatory particle caps. Each sub-complex is further composed of several protein subunits.&#160;
Multiple proteasome-dedicated chaperones integrate these subunits into their respective sub-complexes. Finally, chaperones assemble the sub-complexes into the complete proteasome complex.

protein complex assembly

Eiwitcomplexassemblage

Eiwitten kunnen homomere complexen vormen door binding met een andereidentieke eenheid van hetzelfde eiwit of heteromere complexen door interactie met verschillende typen.soorten eiwitten. De meeste eiwitcomplexen assembleren zichzelfzelfassembleren spontaan via geordende routes, terwijl sommige eiwitten assemblagefactoren nodig hebben die hunde juiste assemblageopbouw begeleiden. Ondanks de drukke intracellulaire omgeving interagerenbinden eiwitten gewoonlijkmeestal met hun juistecorrecte partners en vormen zeom functionele complexen te vormen.

Veel virussen assembleren zichzelf tot een volledig functionele eenheid, waarbij ze gebruiken de geïnfecteerde gastheercel gebruiken om alle noodzakelijkebenodigde componenten te produceren. Het en vervolgens zelf te assembleren tot een volledig functionele eenheid. Een klassiek voorbeeld hiervan is het tabaksmozaïekvirus (TMV) is een klassiek voorbeeld van), een zelfassemblerend complex van eiwitsubeenheden en RNA. Het zelfassemblageproces van TMV vormt de basis voor enkele van desommige therapeutische virusdeeltjesvirale deeltjes die zijn ontworpenworden ontwikkeld voor medicijnafgiftegeneesmiddeltoediening.

Sommige eiwitcomplexen assembleren zichzelf alleen als gevolg van mutaties of aandoeningen. HemoglobineEen voorbeeld hiervan is hemoglobine, het zuurstofdragende eiwit dat in rode bloedcellen wordt aangetroffen, is , dat normaal gesproken een tetrameer vantetramere structuur heeft bestaande uit twee alfa- en twee bèta-subeenheden.bètasubeenheden. Bij sikkelcelanemie vervangtveroorzaakt een enkele puntmutatie echter een hydrofielde vervanging van het hydrofiele aminozuur glutamine door eenhet hydrofobe aminozuur valine. Hierdoor ontstaan kleverige hydrofobe plekken aan de plakgebieden op tegenovergestelde zijden van het hemoglobinetetrameer.hemoglobinetetramer. In eende waterige celomgeving hechtenomgeving van de cel binden deze hydrofobe plekken op verschillendegebieden zich aan andere hemoglobinemoleculen zich en worden ze samengevoegd tot, waardoor lange en stijve vezels ontstaan. Deze vezels veranderen de vorm vanvervormen de rode bloedcellen van een sferoïde normale sferische vorm naar een halvemaanvormige vorm.sikkelvorm.

Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types.&#160; Most protein complexes ...

Education

JoVE Core

Cell Biology

Celbiologie

Unit 1

Eenheid 1

Protein Structure

Eiwitstructuur

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

Eiwitcomplexassemblage

protein complex formation and function

Protein complex formation explains how proteins join together to carry out specific jobs in cells. These groups are called protein complexes, and they can form in more than one way. Some complexes are homomeric, which means they contain the same kind of protein subunit. Others are heteromeric, which means they contain different protein subunits.

The assembly process helps show how protein shape and subunit choice affect function. When proteins combine, the resulting complex can behave differently from a single protein working alone. Understanding this process is important for studying how cells build active molecular machines and organize their internal work.

Protein Complex Formation and Function

what are proteins?

Protein Building Blocks and Folding

Proteins are built from amino acids linked by peptide bonds. Long chains of amino acids are often called polypeptides, and the terms proteins and polypeptides are sometimes used the same way. In this context, polypeptides with a molecular weight below 10,000 daltons are called polypeptides, while proteins have a higher molecular weight. Very short chains with fewer than 20 amino acids are called peptides or oligopeptides. Amino acids are the basic units of proteins. Each amino acid has a...

protein organization

Protein Folding Levels and Bonds

Proteins are built from amino acids and folded into shapes that support many cell jobs. They help with DNA replication, molecular transport, catalysis, and structural support. Their function depends on how their amino acids are arranged and folded. Protein structure is organized in levels. The primary structure is the amino acid sequence in a polypeptide chain. Amino acids are joined by peptide bonds, and the chain has two ends: the amino terminus, or N-terminus, and the carboxyl terminus, or...

protein folding

How Amino Acid Sequence Shapes Proteins

Proteins get their shape from the order of amino acids in a polypeptide chain. After a protein is made, the chain folds into a three-dimensional form that is needed for it to work. The way amino acids interact with one another guides this folding. Protein structure matters because proteins do many jobs in cells. They can speed up chemical reactions, help with immune defense, store materials, carry substances, send cell signals, support movement, and provide structure. A protein usually works...

protein families

Protein Families and Superfamilies

Protein families and superfamilies group proteins with shared features. These groups help scientists organize proteins by common structure, function, or evolutionary history. The classification can show how related proteins are connected across different organisms. A protein family usually includes proteins that are closely related. A superfamily is a broader group that can include several families with more distant relationships. These categories help explain why some proteins share similar...

conservation of protein domains

Protein Domains Shared Across Proteins

Protein domains are shared structural and functional parts of proteins. A domain is a region that can often be found in more than one protein, even when the full proteins are different. This conservation means that a protein domain may keep a similar shape or role across related proteins. Because of that, scientists can compare proteins by looking for domains that stay the same. Conserved domains help reveal how proteins are related and how they may work. The topic of protein domain...

globular and fibrous proteins

Protein Shapes: Globular vs Fibrous

Proteins can have globular or fibrous shapes, and these shapes help explain how they work in the body. Globular proteins are compact and usually fold into rounded forms. Fibrous proteins are long, extended molecules that often provide support and structure. The shape of a protein is tied to its function. Globular proteins often take part in chemical jobs in cells, while fibrous proteins are better suited for strength and stability. These structural differences make the two groups easy to...

intrinsically disordered proteins

Flexible Protein Regions and Disorder

Intrinsically disordered proteins have flexible regions that do not settle into one fixed shape. Instead, these proteins can remain dynamic and change form as they move through the cell. This flexibility is an important part of their structure and function. Many proteins need a stable folded shape to work properly. Intrinsically disordered proteins are different because they may lack a single rigid structure under normal conditions. Their shifting shape can help them take part in cell...

Protein complex formation explains how proteins join together to carry out specific jobs in cells. These groups are called protein complexes, and they can form in more than one way. Some complexes are homomeric, which means they contain the same kind of protein subunit. Others are heteromeric, which means they contain different protein subunits. The assembly process helps show how protein shape and subunit choice affect function. When proteins combine, the resulting complex can behave...

conjugated proteins

Conjugated Proteins and Their Bound Groups

Conjugated proteins are proteins that include a nonprotein part called a prosthetic group. This added group helps give the protein its full structure or function. The video explains how the protein part and the bound group work together. Several common types of conjugated proteins are named by the kind of group attached. Nucleoproteins contain nucleic acids. Glycoproteins contain carbohydrate groups, and lipoproteins contain lipid groups. Other examples include phosphoproteins, which have...

amyloid fibrils

Amyloid Fibrils and Protein Aggregation

Amyloid fibrils are protein aggregates with a very specific structure. They are made when proteins misfold and stick together in long, ordered fibers. This structure makes them different from many other protein clumps. Amyloid fibrils are important in biology because they are linked to protein aggregation. Protein aggregation means proteins build up into groups instead of staying properly folded and separate. In many cases, this process is associated with disease and abnormal cell function. <br...

key terms and concepts

Learn how protein complexes form from homomeric and heteromeric subunits, and how assembly changes protein function in cells.

Protein Complex Formation and Function | 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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Conservation of Protein Domains

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Globular and Fibrous Proteins

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Intrinsically Disordered Proteins

Ribosomes

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Protein and Protein Structures

Conjugated Proteins

Proteins: From Genes to Degradation

Amyloid Fibrils

What are Proteins?

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Ligand Binding Sites

Protein Organization

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Protein-Protein Interfaces

Protein Folding

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protein-complexes-with-interchangeable-parts

Protein Complexes with Interchangeable Parts

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Structural Protein Function

Protein Networks

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.]

Levels of Organization

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Overview of Human Digestion

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Homeostasis
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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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pH Homeostasis

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HS-LS1-3

Protein Complex Formation and Function

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