Construct design, expression, and purification from µg to g.
We specialize in providing customized solutions for recombinant protein production supported by in-house gene synthesis capabilities for seamless project initiation. Whether you require modifications to existing proteins or entirely novel constructs, we are committed to delivering active protein solutions that are, efficient, scalable, and functionally robust. Our recombinant protein production experience along with our proprietary SAMS™ platform will ensure your product has the optimal configuration and protein expression conditions for bioactivity and purity.
How it works
Seamless collaboration & transparent solutions
Our expert team will collaborate with you to ensure the final product meets your specific criteria. We strive to make your experience seamless and productive, which is why we're transparent in turnaround times, costs, and success probabilities. Partner with us to advance your scientific discoveries and bioprocessing projects with reliability and ease through our Protein Expression Service and end-to-end Protein Services.
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Custom Protein Expression Workflow
Our custom protein services are designed to provide communication, transparency, and quality. This workflow ensures that your custom protein needs are met according to your standards.
- Initial discussion We begin by evaluating your project goals and design parameters. This includes reviewing your expression vector construction, gene synthesis, host systems, and codon optimization strategies.
- Protein development and expression We design, express, and optimize constructs using platforms such as mammalian cells, E. coli, yeast, or Baculovirus expression systems– well-suited for producing complex proteins, including membrane proteins, using both stable and transient protein expression techniques.
- Quality Control and Quality Assurance Throughout the workflow, QC steps are taken—such as endotoxin testing, protein characterization, western blot analysis and affinity chromatography—to ensure the final product meets expected performance metrics.
Customization Types
Customize a Catalog Protein
Our team can modify parameters such as tags, biotinylation, and fluorescent labels, to ensure the product aligns with your precise requirements. You can select Protein Tags and request protein conjugation for targeted applications. This option provides a cost-effective and efficient solution by leveraging our established product base while meeting your unique specifications.
Create a Novel Protein
For more specialized needs, we offer the expression of unique protein constructs, including fusion proteins or Fc-fusion proteins. Our research team will design, express, and purify proteins of interest, with your tags, cleavage sites, buffers, concentrations, quantity, etc. This service ensures you receive a customized solution, supported by detailed QC data that drives your research forward and supports groundbreaking discoveries.
Service Details
What information is needed to start?
To get started, our scientific team will work with you to review all necessary conditions and requirements. We'll discuss the gene to protein workflow, gene sequence accuracy, expression vector construction, buffers, quantity, and downstream processing methods such as protein purification or size exclusion chromatography. This ensures we understand your specific needs and can deliver precisely what you're looking for. Simply provide us with as many project details as you can, and we'll guide you through the rest.
What is the typical turnaround time?
The majority of our custom protein expression can be accomplished in 6-8 weeks. Various factors such as quantity, difficulty of expression, and bioactivity testing requirements, can increase or decrease this time. Request a quote for your specific requirements and we'll provide a more detailed timeline.
What expression systems are offered?
Mammalian Expression
We offer scalable production using mammalian cell lines such as HEK293 for recombinant proteins. Our optimized expression system ensures reliability for intracellular, secreted, and transmembrane, and other membrane proteins.
E. Coli Expression
Our bacterial systems support high-yield protein production and purification of recombinant proteins at large-scale, ensuring reliability and reproducibility. Additionally, our E. coli expression system is cGMP certified and with bioreactors up to 1000L. Learn more about our GMP production.
Insect Expression
Insect cells can express proteins with unique post-translational modifications different from mammalian cell-expressed proteins while still with high yield. The insect cell is a proven robust system for producing proteins with animal health applications.
Yeast Expression
Yeast expression systems offer high product yield and scalability, with easy genetic manipulation to produce proteins with desired properties not achievable in bacterial cells.
Explore our most popular custom solutions
Membrane Proteins
Custom membrane proteins displayed on VLPs or Nanodiscs.
Soluble TCR Expression
Soluble TCR Expression services with engineering, and optimization of various formats of TCRs.
SPR Analysis Services
Characterization of biomolecular interactions using Surface Plasmon Resonance technology.
Solute Carrier Proteins
Custom solute carrier protein expression services displayed on VLPs or Nanodiscs.
Why choose KACTUS?
Structure Optimization
Optimized protein configuration to enhance specificity, sensitivity, and yield.
Purity & Bioactivity
Analyzed for purity and bioactivity to ensure successful application.
Large Batch
Large-scale production batches with batch-to-batch consistency.
Custom Protein Expression Services FAQs
To begin, you’ll need to provide your target protein sequence, along with any preferences for tags, purity requirements, expression system, endotoxin level, buffers, and desired yield. Our team will walk you through the process to ensure all specifications are clearly defined.
Turnaround time is typically 6–8 weeks including shipping, depending on factors such as protein complexity, expression system, and whether bioactivity testing is required. We provide a tailored timeline during project scoping.
We offer a range of systems, including mammalian (HEK293, CHO), bacterial (E. coli), and insect expression systems. Selection depends on your protein’s characteristics, yield requirements, and intended use.
We support flexible production scales, from microgram (µg) quantities for early research to kilogram (kg) levels for preclinical studies or bulk supply. Batch-to-batch consistency is maintained at all scales. Minimum amounts depend on the protein type, please ask us when discussing your custom project.
Yes. You retain full IP rights to your sequence and the final product. KACTUS acts solely as a contract research and manufacturing partner and does not claim ownership of client-submitted sequences or outcomes.
Proteins are shipped either lyophilized or in solution, based on your preference. Each shipment includes storage and handling instructions, and we ensure cold-chain logistics for temperature-sensitive products.
We conduct comprehensive QC, which may include SDS-PAGE, HPLC, endotoxin testing, SPR, and ELISA. If you have specific functional assays or purity requirements, we can incorporate those into the QC plan. Speak with us to determine what QC is included on your project and what QC you may be interested in adding.
Yes. We offer a wide range of custom modifications, including affinity tags, fluorescent labels, biotinylation, cleavage site inclusion, and more. Purification can also be tailored to your research or clinical needs.
We can express a broad spectrum of protein types, including membrane proteins, cytokines, enzymes, VLPs, nanodiscs, and complex fusion proteins such as MHC-peptide fusions. Our SAMS™ platform helps optimize even hard-to-express constructs.
Yes. While this service page focuses on research-grade proteins, we offer GMP production options through our extended services. If your project progresses toward therapeutic development, we can support scale-up and compliance transitions.
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Learn more about KACTUS
TECHNOLOGY PLATFORM
SAMS™ Protein Engineering Platform
Our proprietary protein engineering platform uses bioinformatics and 3D modeling combined with in vitro expression condition testing to optimize protein configuration.
PROTEIN QUALITY
Quality Control
We offer strict quality control testing on custom proteins including SPR, ELISA, purity, and endotoxin. Let us know the specific quality requirements for your project.
OUR COMPANY
About Us
We are a recombinant protein and enzyme company known for tackling the most difficult-to-express proteins. We focus on unmet protein requirements in drug discovery and beyond. Our values our grounded in quality products and quality service.
60 Hickory Drive
Waltham, MA 02451
United States
Custom Recombinant Protein Expression Services | KACTUS