G&P Biosciences offers custom recombinant protein expression and purification services using mammalian cell expression systems for small or bulk quantities of protein production. Mammalian cell expression systems provide the most comprehensive post-translational modifications, which are often critical to the protein activities. For example, therapeutic proteins such as antibodies often require glycosylation that can only be achieved in mammalian expression systems.

We have developed unique mammalian cell expression systems that are based on our high-throughput gene expression technologies, allowing significantly improved success rates and production yields.  Our custom-made recombinant proteins are expressed in mammalian cells growing under animal component-free condition, purified to the highest quality possible, and formulated into the carrier-free or customer-specified buffer suitable for downstream in vitro & in vivo assays.

Custom Recombinant Protein Production

(Service Code: PS-001)

We provide custom recombinant protein production using suspension mammalian cells (HEK293 or CHO) growing in chemical-defined media, allowing large-scale protein production up to gram level. We can conduct custom protein expression through both transient and stable transfection. Typically custom-made recombinant proteins are expressed and purified via a His-tag or as a fusion protein, e.g., human IgG1-derived Fc- or GST-fusion that often increases protein expression level, solubility and/or yield. Additional epitope tags (e.g., HA, Myc), fluorescent proteins (GFP, RFP), enzymes (HRP, luciferase) and other affinity tags (e.g., StreptAvidin, Protein A or G) can also be used for monitoring expression and further purifying your protein of interest (see the list of tags & fusions below).  

Our custom-produced recombinant proteins normally exceed 90% purity as detected by SDS-PAGE analysis. The purified proteins can be formulated into any standard buffer (e.g., sterile PBS pH7.4) or a customer-specified buffer. Our recombinant protein production services are priced according to the required amount and purity of products as well as optimization work needed, e.g., the number of different culture conditions or transfection methods tested. A small pilot production (50-100 ml of culture) is usually conducted to assess the feasibility to express and purify your protein of interest.

We have a collection of pre-made, high quality, recombinant proteins, including cytokines, growth factors, neurotrophins, soluble cell surface receptors, and transporters as well as various enzymes. They can be searched to retrieve your protein of interest by key word, protein synonym, family, classification, disease association, and biological pathway click here to search and order your protein of interest.  If you cannot find your protein of interest in our product catalog or need a different format or variant, we can express and purify it as a custom service project. To discuss your project and request more information, please contact us by email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Bundled Service Package

One-Stop Shop Solution: Gene-To-Protein

(Service Code: PS-G2P)

We offer bundled custom protein expression and purification service, “Gene-to-Protein”, a one-stop shop solution with standardized workflow and turnaround time. Bundle discount is included when you order the target gene expression construct and purified recombinant protein from G&P Biosciences at the same time. We can amplify your target gene from the template you provide or synthesize the gene with optimized codon sequence for expression. We can subclone your target gene into our unique expression vectors for transient and/or stable expression of your protein of interest.  You have the options with different formats (e.g., truncations, mutations), splicing variants, fusions or tagsto choose from (see the feature list above). Your protein of interest will be purified to the highest purity possible using appropriate affinity resin and chromatography steps.

To request this bundled service, simply provide us the DNA nucleotide or protein amino acid sequence for the target gene to be delivered, and indicate the host, fusion or tag to use. If the protein sequence entered, select the species of expression host to use for codon optimization, e.g., human or hamster. Upon receipt of your request, our service team will contact you with the optimized sequence, detailed construct design, purification methods, pricing, and timeline information tailored to your needs.

Data Example

Three different custom protein production projects are shown below as examples to demonstrate the promptness and efficiency of our one-stop shop solution, “Gene-to-Protein” services:

Example #1

The client requested custom production of a human neuron growth factor(~170 amino acids) using mammalian cells. We synthesized codon-optimized target gene and subcloned it into our mammalian expression vector containing a C-terminal His-tag. The construct was transfected into 293 cells and stable cells were generated in 2 weeks. A pilot production (50ml of culture) was conducted to assess the feasibility to express and purify the protein of interest (see the gel image below on the left). 

The conditional media were cleared and loaded onto a Ni2+-NTA column.  After extensive washing, bound proteins were eluted into a series of fractions (E1—E7). SDS-PAGE analysis showed an abundant ~20 kDa protein species present in the fractions E2-E7, matching the correct size of protein of interest.  The process was further scaled up and 1 mg of purified protein of interest (>95% pure in a customer-specified buffer) was delivered to the client in just 5 weeks. Additional studies by the client indicated that the purified protein of interest is active in inducing neuronal cell growth.

Example #2

The client requested custom production of a human enzyme X (~780 amino acids with a calculated molecular weight of ~86 kDa) using mammalian cells. We synthesized the codon optimized target gene and subcloned it into our mammalian expression vector (with a His-tag).  The DNA construct was transfected into 293 cells (500 ml culture) and protein of interest was purified from the cell extracts using Ni2+-NTA and size exclusion chromatography.  0.5 mg of purified protein was delivered to the client in just 5 weeks.  SDS-PAGE analysis showed that the purified protein is >95% pure and runs at the correct size as calculated M.W. (see the gel image in the middle). The client tested and utilized our purified protein to develop an enzymatic assay for compound screening.

Example #3

The client requested custom bulk production of a Fc-fusion protein for the extracellular domain (~230 amino acids) of cell surface receptor Y.  We synthesized the codon optimized target gene in frame fused with the Fc region of human IgG1 and subcloned it into our mammalian expression vector. The construct was introduced into CHO cells and stable cell lines were generated and further expanded for protein production (total 6 liter culture). 100 mg of purified Fc-fusion were delivered to the client in just 9 weeks. SDS-PAGE analysis showed the purified Fc-fusion is >95% pure and exists as a dimer under non-reducing condition (DTT: “—”) or as a monomer under reducing condition (see the gel image below on the right, DTT: “+”)). The client further used the purified Fc-fusion protein in their functional studies of ligand binding and neutralization efficacy.

At G&P Biosciences, we are determined to provide you the best custom protein production services in the most time-effective way. With decades of experience in protein expression and purification, we excel on all aspects of the production process (gene synthesis, cell culture, transfection, protein expression and purification as well as scale-up). We have successfully delivered custom recombinant proteins to our clients with a very high on-time rate. Ultimately our goal is to be a partner you can trust and depend on to produce your protein of interest.