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
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.
Request Custom Protein Expression Services
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.