Proteins

Creative Biolabs can generate a variety of complement system-related proteins, which could be qualified tools for the early discovery process in life science research and groundbreaking development of specific clinical applications.

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Complement Proteins

Creative Biolabs is committed to advancing immunology research with a comprehensive suite of complement proteins that support specific research needs across the classical, lectin, alternative, and terminal pathways. Our high-quality proteins empower researchers to uncover critical insights into immune responses, inflammation, and infection mechanisms, driving innovations in therapeutic development and immunology. Whether your work involves studying pathogen recognition, immune complex clearance, or complement-mediated cell lysis, Creative Biolabs offers a robust and customizable solution to meet your research needs.

Components of the Complement System

Initially discovered in the 1890s as a heat-labile component of plasma that "complemented" antibodies in bacterial lysis, our understanding of this system has evolved dramatically. The evolutionary conservation of complement components across species underscores its fundamental importance in immune defense. The complement cascade comprises over 30 plasma proteins and membrane-bound regulators that interact in a precisely orchestrated manner. These proteins typically circulate in inactive zymogen forms, requiring specific proteolytic cleavage for activation. This sophisticated activation mechanism prevents unnecessary inflammation and tissue damage while maintaining a rapid response capability.

Activation Pathway	Description	Key Components
Classical Pathway	The classical pathway represents the antibody-dependent activation route of the complement system. The pathway initiates when C1q recognizes antibody-antigen complexes or other activation surfaces, leading to conformational changes that trigger the cascade.	C1 Complex: Consists of C1q, C1r, and C1s molecules C4: Cleaves into C4a and C4b fragments C2: Forms C3 convertase when combined with C4b
Lectin Pathway	The lectin pathway provides antibody-independent activation through pattern recognition. This pathway recognizes carbohydrate patterns on microbial surfaces, providing an immediate response to pathogen invasion.	Mannose-binding Lectin (MBL): Recognition molecule Ficolins: Pattern recognition molecules MBL-associated Serine Proteases (MASPs): Enzymatic activators
Alternative Pathway	The alternative pathway maintains constant low-level activation through spontaneous C3 hydrolysis. This pathway serves as an amplification loop for all complement activation routes.	Factor B: Forms alternative C3 convertase Factor D: Cleaves Factor B Properdin: Stabilizes alternative pathway convertases

Complement Proteins Portfolio

Creative Biolabs is a leader in providing high-quality, research-grade complement proteins that support advanced studies in immunology, inflammation, and infection. Our complement protein portfolio is designed to facilitate groundbreaking research, with each product optimized for specific experimental needs.

C1q

Role: C1q binds to the Fc region of IgG or IgM in immune complexes, initiating the classical pathway.
Research Applications: Studies on autoimmune disorders, antibody responses, and immune complex clearance.
Product Variants: Recombinant human and animal-derived C1q proteins for in vitro research.

C1r and C1s

Role: C1r and C1s are serine proteases activated upon C1q binding, cleaving downstream complement proteins (C2 and C4) to amplify the complement cascade.
Research Applications: Investigations of antibody-antigen interactions, complement deficiencies, and inherited complement disorders.
Product Variants: Highly purified forms suitable for functional assays and structural studies.

Lectin Pathway Proteins

Our portfolio provides comprehensive tools for probing the lectin pathway, allowing insights into innate immunity and inflammation research.

MBL

Role: MBL recognizes and binds to carbohydrate patterns on pathogen surfaces, recruiting MASPs to activate downstream complement components.
Research Applications: Studies on host-pathogen interactions, inflammation, and innate immune deficiency disorders.
Product Variants: Recombinant and native MBL suitable for binding and complement activation studies.

MASP-1, MASP-2, and MASP-3

Role: MASPs are serine proteases that cleave C4 and C2, forming C3 convertase, a crucial enzyme for the Lectin Pathway.
Research Applications: Investigation of pathogen recognition, lectin pathway activation, and MASP-related genetic disorders.
Product Variants: Recombinant MASP proteins in various isoforms for biochemical and functional studies.

Alternative Pathway Proteins

Our alternative pathway proteins support innovative research into non-antibody immune responses, crucial for understanding immune surveillance mechanisms.

Role: C3 undergoes spontaneous hydrolysis, which enables the formation of C3 convertase, essential for opsonization and immune cell recruitment.
Research Applications: Studies on pathogen opsonization, immune complex clearance, and C3-associated diseases.
Product Variants: Recombinant and purified C3 proteins, including active and inactive forms for mechanistic studies.

Role: Cleaved by C5 convertase into C5a and C5b, with C5a acting as a potent inflammatory mediator and C5b initiating MAC formation.
Research Applications: Research on inflammation, chemotaxis, and complement-associated autoimmune diseases.
Product Variants: C5 and its active fragments, tailored for inflammation and chemotaxis studies.

Properdin

Role: Properdin stabilizes the C3 convertase complex on pathogen surfaces, enhancing the pathway's amplification loop.
Research Applications: Studies focused on the stabilization and amplification of the alternative pathway and properdin deficiencies.
Product Variants: Native and recombinant properdin, suitable for in-depth studies of complement stability and amplification.

Terminal Pathway and Membrane Attack Complex (MAC) Components

Our portfolio includes each of these MAC components, supporting research on cell lysis, apoptosis, and complement-mediated cytotoxicity. These products facilitate in-depth exploration of the terminal pathway, enabling studies on immune cytotoxicity and the potential therapeutic targeting of MAC formation.

C5b

Role: C5b initiates MAC formation by sequentially recruiting C6, C7, C8, and C9 to form a pore on the target membrane.
Research Applications: Studies on complement-mediated cell lysis, apoptosis, and membrane repair mechanisms.
Product Variants: Purified C5b for MAC reconstitution and functional assays.

C6, C7, C8, and C9

Role: These proteins sequentially assemble with C5b, creating the transmembrane pore that leads to cell lysis.
Research Applications: Complement-mediated apoptosis, cancer cell lysis studies, and drug testing for MAC inhibitors.
Product Variants: Recombinant C6, C7, C8, and C9, optimized

Complement Protein Products in Research

Complement proteins play essential roles in the immune system by enhancing immune responses through a complex cascade. This cascade not only amplifies the immune response but also aids in immune cell recruitment, pathogen lysis, and inflammation mediation. Over recent years, complement proteins have become a focal point of study across various research fields.

Research Areas	Diseases/Mechanisms	Role of Complement Protein
Immunology and Autoimmune Disease Research	Systemic Lupus Erythematosus (SLE)	C1q is essential for studying apoptotic cell clearance defects, a hallmark of lupus pathogenesis, and helps understand the autoantibody production and immune complex deposition seen in SLE.
	Rheumatoid Arthritis (RA)	C5a and MAC are often upregulated in RA. Researchers use these complement pathways to mimic the synovial inflammation and tissue destruction that characterize RA.
	Multiple Sclerosis (MS)	Complement activation products like C3b and C5a are detected in demyelinating lesions.
Infectious Disease Research	Bacterial Pathogens	Many bacterial pathogens produce proteins that bind to host complement regulators (e.g., Factor H) to prevent complement activation on their surfaces.
	Viral Pathogens	Viruses modulate complement activation to evade immune detection.
	Fungal Pathogens	Fungi also employ complement evasion strategies.
Cancer Research	Immune Modulation and Evasion	Tumors may upregulate complement inhibitors like CD55 or CD59 to prevent complement-mediated lysis.
Cancer Research	Tumor-associated Inflammation	Studies show that blocking C5a receptors can prevent inflammation-driven tumor growth in models of lung cancer.
Neuroinflammation Research	Alzheimer's Disease (AD)	Studies on C1q and C3 reveal how excessive complement activation promotes microglial phagocytosis of neurons, which accelerates cognitive decline.
Neuroinflammation Research	Multiple Sclerosis (MS)	Models using complement inhibitors (e.g., anti-C5 monoclonal antibodies) show that reducing complement activation reduces inflammation and lesion formation.
Vaccine Development	Adjuvant Efficacy Enhancement	For example, vaccines that include adjuvants activating the C5a pathway show enhanced T-cell activation
Vaccine Development	Targeted Immunomodulation	Researchers use complement-activated peptides or proteins to promote stronger and longer-lasting immune responses.

Product Quality and Customization Options

Creative Biolabs, with over two decades of experience in the biotechnology industry, offers an extensive suite of complement protein products and customization options tailored to meet the precise needs of research labs worldwide.

1

Product purity and activity

We use rigorous purification methods to produce complement proteins of the highest purity. Each batch is meticulously analyzed for activity levels.
2

Lot-to-lot consistency

We use standardized procedures and advanced analyses to confirm that each batch meets the required specifications, providing researchers with a reliable tool for their work.
3

Meeting industry standards

Our manufacturing facilities follow Good Manufacturing Practice (GMP) guidelines and other relevant industry certifications.

Our advanced recombinant protein technology allows Creative Biolabs to produce stable, active complement proteins with unparalleled precision. We use state-of-the-art expression systems and optimization techniques to ensure protein functionality and stability even under demanding research conditions.

High-yield expression systems

Creative Biolabs utilizes high-yield expression systems (e.g., mammalian, bacterial, yeast, and insect cell lines) that can be tuned to the specific needs of each protein.

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Proprietary stabilization technologies

Our proprietary stabilization technologies are designed to improve the durability and activity of complement proteins under a variety of storage and handling conditions.

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Customized Complement Protein Production

Recognizing that research needs can vary widely, Creative Biolabs offers a range of custom options for complement protein production. Whether targeting a specific modification, labeling, or conjugation, our customization services are designed to meet unique research needs and ensure that each protein product is best suited for its intended use.

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Protein modifications

Labelling and binding services

Customized technical consultation

Complement Protein Assays and Functional Testing Solutions

Assays that analyze complement protein activity are essential tools for understanding complement-mediated mechanisms and their effects on cellular and molecular responses. We provide an in-depth overview of various assay formats and solutions, assisting researchers in selecting appropriate complement proteins for functional studies.

Assays	Descriptions	Applications
Hemolytic Assays	Hemolytic assays are foundational for studying the classical pathway of complement activation, primarily used to assess complement-mediated cytotoxicity.	Specificity for classical pathway: By utilizing antibody-coated RBCs, these assays selectively trigger the classical pathway, allowing researchers to isolate the effects of classical complement components.
		Quantitative assessment of complement activity: The extent of hemolysis directly correlates with complement activity levels, providing an effective method for evaluating complement function.
		Reproducibility: Hemolytic assays are well-established and reproducible, making them suitable for comparative studies across different complement conditions or experimental models.
C1q-Binding Assays	The binding ability of developed antibodies to complement C1q and resultant complement classical cascade activation is an important aspect for measuring the efficacy and safety of therapeutic mAbs.	C1q-binding assay is necessary for characterization during the development process of therapeutic mAbs.
C1q-Binding Assays		ELISA and SPR methods are available in Creative Biolabs for C1q binding assays.
MAC Formation Assays	MAC formation assays are specifically designed to assess the activity of the terminal complement pathway (C5 through C9). MAC formation assays are commonly conducted using cell lines or liposomes susceptible to complement-induced lysis. Fluorescent dyes or radioisotopes are often employed to measure MAC-induced membrane disruption, allowing quantification of complement activity.	Comprehensive pathway activation analysis: By triggering the terminal complement pathway, these assays provide detailed insights into the complete complement activation process.
		Evaluating complement inhibition: MAC assays are instrumental in screening for complement-targeting drugs, allowing researchers to quantify the inhibition of terminal pathway components.
		Sensitivity to pathway-specific activation: These assays can be adapted to measure lysis mediated by different complement pathways, offering flexibility for tailored experimental designs.
Cell-based Complement Activity Assay	Cell-based complement activity assays enable the direct assessment of complement activation and its consequences on target cells, mimicking in vivo conditions more closely than traditional biochemical assays.	Complement activity assays have gradually emerged as a powerful tool to study the complex interactions between complement components and their target cells.
Cell-based Complement Activity Assay		Indirect Immunofluorescence Assay (IFA Assay) Cell-Enzyme-Linked Immunosorbent (ELISA) Assay

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Creative Biolabs offers a range of high-quality products for complement activity and function assays. View our product list to find your interested products.

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Complement Function Analysis Protocols

We briefly summarize the complement-related assay protocols. Find complement-related assay protocols by clicking the following items.

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FAQs

How can I use complement proteins in my experiments?

Complement proteins can be utilized in various experimental settings, such as immune assays, complement activation tests, and inflammation models. For example, you can use them to trigger the classical or alternative pathways in vitro or observe their effects in cell cultures or animal models. It's essential to select the appropriate complement proteins based on the research focus, whether it's studying opsonization, cell lysis, or inflammatory responses.

Are your complement proteins sourced from human or animal sources?

Our complement proteins are derived from both human and animal sources, depending on the specific product. Human complement proteins are often preferred for studies that aim to mimic human physiological conditions, while animal-derived proteins may be suitable for certain types of research. All products are thoroughly tested for quality and activity to ensure they meet research-grade standards.

How should I store complement proteins to maintain their stability?

Complement proteins should be stored at -20°C or -80°C to ensure their stability. Some proteins may require reconstitution in specific buffers to preserve their function. It's also essential to handle them with care to prevent contamination or degradation. Detailed storage instructions are provided with each product, and we recommend following them closely to ensure optimal performance during experiments.

Can I use complement proteins in diagnostic or clinical applications?

Our complement proteins are intended solely for research use and are not approved for diagnostic or clinical applications. They can be used in various in vitro experiments to study immune mechanisms or to develop therapeutic strategies, but any clinical application would require additional testing and regulatory approval. We encourage you to consult with regulatory bodies if your research progresses toward clinical applications.