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Custom Protein Service

Can't Find The Recombinant Protein You Need?

RayBiotech has provided Custom Protein Services since 2006. Our comprehensive service program covers every step of production from gene cloning through protein purification, and includes downstream processing such as protein desalting, lyophilization, vialing, and conjugation to tags, fluors, or other labels. If you can’t find your protein of interest on the market, please contact our technical support team to discuss your project and create a custom quote. Our expert team of scientists is here to help you achieve your research goals.

Custom Protein Request Form

Service Features

✔ Complete. Gene cloning/gene synthesis to protein purification.
✔ Fast Turnaround. 3 weeks for bacterial expression; 4-5 weeks for mammalian cell expression.
✔ Optimization. Our expert team of scientists can strategically alter expression vectors or host systems to obtain optimal gene expression.
✔ High Purity. Typically >95% purity. (SDS-PAGE)
✔ Protein Processing. Desalting, aliquoting, lyophilization, and conjugation services are available to your specifications.
✔ Competitive Prices. Ask about our introductory discount for first-time customers!
✔ Low-Risk. Close coordination by our technical support team with updates on each milestone phase of project. Customer is only billed for milestones successfully completed.

Gene Expression Systems

RayBiotech offers 4 different gene expression systems to serve a variety of research requirements. See chart below for a comparison of features and specifications.

Comparison of Available Gene Expression Systems

 CharacteristicsBacteriaYeastInsect Cells (Baculovirus)Mammalian Cells (TruExp)
General Features Expression Level Low-Medium-High Low-High Low-High Low-Medium-High
Cell Doubling Time Rapid (30min) Rapid (30min) Slow (18-24hr) Slow (24hr)
Cost Low Low High High
Time Line 3 Weeks 3-4 Weeks 6-8 Weeks 4-5 Weeks
Post-Translational Modifications Protein Folding Not Reliable Reliable Very Reliable Very Reliable
Glycosylation None Not indentical to mammalian systems.
High Mannose.
Not identical to mammalian systems.
Simple, no sialic acid
Complex, authentic
Phosphorylation None Yes Yes Yes
Acetylation No Yes Yes Yes
Acylation No Yes Yes Yes
gamma-carboxylation No No No Yes

RayBiotech TruExp Mammalian Cell Gene Expression System

TruExp is a state-of-the-art mammalian cell-based expression system developed by RayBiotech which efficiently delivers recombinant proteins with native conformations and post-translational modifications (PTMs). A result of years of effort by the R&D team, TruExp is an ideal system for the production of mammalian proteins which must retain some or all of their native functions, and an excellent option for high molecular weight or difficult to express proteins.

✔ Complex, abundant PTM. See Figure 1
✔ High Expression. Typical yield ranges from 2 - 355 mg purified protein per liter of culture (Figure 1, Table 1).
✔ Secretion. Expressed protein is secreted into the culture medium, facilitating high purity levels (in contrast to recovering protein from highly contaminated lysate fractions) (Figures 1 & 2).
✔ Multiple Tags. Choose from a variety of removable fusion tags (i.e., His, myc, Fc, GFP, etc.).
✔ Scalable. Suspension cell cultures easily scale up to 10 liters or more.
✔ No Biohazard. Serum-free medium and animal source-free materials eliminate biohazard risk.

Custom Protein

Figure 1. Raybiotech TruExp Mammalian Cell Gene Expression System demonstrates gene over-expression and secretion. Six human genes (H1-6) and 3 mouse genes (M1-3) were expressed by the TruExp expression system. Cell culture supernatants (10 µL) were applied to 12% SDS-PAGE (A) and Western blot probed with anti-his tag monoclonal antibody (B). Except for genes H6 and M2, all overexpressed genes display additional secreted protein bands (A, red arrows). All genes were expressed, with some displaying abundant post-translational modifications, evident by increased molecular weights compared to the predicted sizes (B, yellow arrows). M = protein standard markers (kDa).

Custom Protein

Figure 2. Representative purified human proteins from Raybiotech TruExp Mammalian Cell Gene Expression System.Affinity-purified recombinant proteins from culture supernatants of transfected mammalian cells exhibit high purity and intact protein bands, even at MW larger than 100 kDa. M = protein standard markers (kDa).

Table 1.Typical recombinant human protein yields of Raybiotech TruExp Mammalian Cell Gene Expression System

Protein NameYield
(mg/L culture)
Serpin B4, Serpin Peptidase Inhibitor SCCA2 335.7
Calcitonin CT 160.8
14-3-3 Protein Epsilon YWHAE 103.1
N-terminal of the prohormone BNP NT-proBNP 99.5
Lipocalin-2 NGAL 69.1
a-Fetoprotein AFP 63.2
Brain natriuretic peptide 32 BNP-32 51.2
Ubiquilin-1 UBQN 41.3
Carcinoembryonic Antigen CEA 39.8
Receptor Tyrosine-Protein Kinase erb-3 erbB-3 37.5
Epidermal Growth Factor Receptor EGFR 23.5
Pepsinogen II, Pepsinogen C PGC 18.6
Lymphocyte Activation Gene 3 Protein LAG-3 16.9
Receptor Tyrosine-Protein Kinase erbB-2 Erb/Her2 16.7
Hepatocyte Growth Factor Receptor HGF R 14.6
Annexin A2 ANXA2 11.8
Golgi Membrane Protein 1 GP73 5.5

Protein Expression Service Overview

Cloning or Sub-cloning of Gene of Interest (GOI)


DNA Sequencing Verification of Recombinant Expression Construct


Gene Expression


Protein Affinity-Purification


Desalting, Aliquoting, Lyophilization, etc.


Ready for Customer

Outline of Recombinant Protein Expression Service in Bacteria

Phase ServiceTimelineDescriptionDeliverables
Phase 1: Gene cloning 1 week Use your expression vectors without any modification N/A
Gene synthesis and codon optimization Recombinant expression vector DNA, 2 µg
Subclone your gene into an expression vector DNA sequencing chromatography data
Phase 2: Large-scale gene expression 1 week Transform DNA sequence-confirmed recombinant plasmid into bacteria Bacterial glycerol stocks transformed with recombinant expression vector, 2 vials, 0.5 mL/vial
Express protein in 2 liters of culture
Collect, lyse and extract the induced cells
Centrifuge to obtain the supernatant fractions for purification
Phase 3: Protein affinity purification 1 week Protein affinity chromatography purification Comprehensive report including induction conditions, method of extraction, SDS-PAGE data, protein concentration, etc.
Determine the protein purity by SDS-PAGE with Coomassie blue staining Affinity purified proteins (95% purity guaranteed)
Protein desalting Aliquoting, lyophilization and conjugation of purified proteins are available upon request
Determine the protein concentration
Concentrate the samples if protein concentration is low

Outline of Recombinant Protein Expression Service in Mammalian Cells

Phase ServiceTimelineDescriptionDeliverables
Phase 1: Gene cloning 1.5 weeks Use your expression vectors without any modification N/A
Gene synthesis and codon optimization DNA sequencing chormatography data. If you provided your own expression vectors, you will also receive: 1. Recombinant expression vector DNA (2 µg); 2. The glycerol stock transformed with plasmid (1mL)
Provide gene template or subclone your genes into either an expression vector provided by you or an overexpression vector from Raybiotech, Inc.
Phase 2: Gene Expression 1-3 weeks Small scale of gene expression: transfect 2 ml of HEK293 suspension cell cultures using the sterile recombinant plasmid DNA SDS-PAGE and Western blotting results
SDS-PAGE and Western blotting analysis to confirm the gene expression, expression levles, protein secretion, protein solubility, etc.
Upon request, perform large scale of gene transfection (100-500 ml)
Centrifuge to obtain the culture supernatant and cell pastes for purification
Phase 3: Protein affinity purification 1.5 weeks Cell lysis, protein extraction, centrifugation, etc. Comprehensive report including induction conditions, method of extraction, SDS-PAGE data, protein concentration, etc.
Protein affinity chromatography purification from lysate and/or cel culture supernatant, desatling, etc. Affinity purified proteins (95% purity guaranteed)
Determine the protein purity by SDS-PAGE with Coomassie blue staining Comprehensive report from gene cloning to protein expression and affinity-purified proteins (protein lyophilization, conjugation, vialling, etc. is up to the customer's request)
Determine the protein concentration. Concentrate the samples if protein concentration is too low
QC process, deliver protein product and project report, etc.

Additional Molecular and Cell Biology Services

To complement our Gene-to-Protein service packages, RayBiotech offers an array of molecular biology technical services for your convenience. These services can be purchased individually or included in your custom service contract. Our technical specialists are available to consult with you and plan a work flow that addresses your specific research goals.

Our molecular biology services include, but are not limited to:

Plasmid DNA, Genomic DNA, and RNA extraction
Gene Synthesis
Quick gene cloning and subcloning
Optimization of gene expression
Protein affinity purification, desalting, lyophilization, etc.
Protein analysis (SDS-PAGE, Western blotting, IP, etc.)
Protein conjugation (i.e., biotin, FITC, streptavidin, nano-particles, etc.)
Cell culturing, cell transfection, cell lysate preparation, etc.
Array printing
Antibody production

To obtain a quotation, please fill out a Custom Protein Request Form or feel free to contact us directly.