90% success rate and above 1500 proteins expressed is the best demonstration of the quality of our protein expression service! What is our winning strategy for high yield protein expression? High performance proprietary protein expression systems, a team of protein experts and dedicated protein production platforms.

Our protein expression in mammalian cell
service is XtenCHOTM inclusive!

XtenCHOTM is the gold standard for protein expression. After many years of intensive research, ProteoGenix released an expression system able to outperform ExpiCHO, the current reference. Check some data on our recombinant antibody production page.

This is only one demonstration of the outstanding performance we can achieve with our proprietary protein expression system. Don’t miss the opportunity to skyrocket your protein production with XtenCHOTM!

Step Content Timeline Deliverables
Gene synthesis
  • Gene synthesis
  • Codon optimization for mammalian expression system
  • Subcloning into an expression vector
4 to 5 weeks
  • Protein test sample
Pilot study
  • Plasmid amplification and preparation
  • Transfection
  • Small scale protein expression
4 to 5 weeks
  • Protein test sample
Transient protein expression and purification
  • Large scale protein expression (1L)
  • Affinity purification
  • QC analysis: SDS-PAGE, concentration
3 to 4 weeks
  • Purified protein
  • Detailed report
Stable cell pool generation
  • Stable transfection
  • Pool selection
12 to 14 weeks
  • Stable pool vials
  • Detailed repor
Stable cell line generation
  • Selection of the best producing clones
  • Clone characterization
  • Stability study
  • RCB preparation
  • Process optimization
20 weeks
  • RCB tested for mycoplasma
  • COA
  • Detailed report with optimized protocol


  • Large scale transient protein expression: 5L, 10L
  • Size exclusion chromatography
  • Polishing (DNA, HCP, endotoxins)
  • Endotoxin removal
  • Analytics : WB, analytical SEC

Protein expression adapted
to your needs

ProteoGenix strives at offering to its customers the most advanced protein production platforms. With XtenCHOTM and our GS deficient cell line, our experts developed their own tools to break the limits of your protein expression and to bring an adapted answer to all your challenges.
Looking for short-term production of multi-gram amount of proteins? Need a cell line for long term recombinant protein production? Don’t go anywhere else, you are at the right place!

Transient protein expression
  • Multi-gram quantities possible (production up to 120L)
  • Timeline: 7 to 9 weeks
  • Short-term production
Stable cell pool generation
  • Long-term production
  • Timeline: 12-14 weeks
Stable cell line generation
  • Multi-gram yield
  • Large scale + long-term protein production
  • Timeline: ≈6 months

Case study: protein expression of a rabbit IgG

Rabbit IgGs demonstrate very high affinity and specificity. However, their very low productivity often limits their use (typical protein expression yield around 20mg/L). ProteoGenix is able to express these antibodies with yields over 200mg/L.

Protein Expression Protocol

A CHO cell culture was transiently co-transfected with vectors coding for Rabbit IgG HC and LC. Cells were harvested 6-days post-transfection. Target antibody was purified by affinity.

mammalian expression purification

Figure 1: Target mAb purification profile. Coomassie blue staining.

Non-reducing analysis.

MW. Molecular weight marker. IN. Input. FT. Flow through. W. Washes. E. Eluted fractions.


After purification, fractions of interest were pooled and final samples were concentrated and buffer exchanged. A final QC of the protein expression was then realized by SDS-PAGE in reduced and non-reduced conditions.

Recombinant antibody production QC

Figure 2: Final QC of purified recombinant mAb. Coomassie blue staining.

2µg of sample loaded per lane

Yield / mg/L Purity / %
Rabbit IgG 265 90

When should you use protein expression in mammalian cells?

Multi-gram protein expression is a pre-requisite for many academic (for example functional analysis, crystal structure determination…) industrial and biopharmaceutical projects. For long, achieving high yields in recombinant protein productions using mammalian cells was considered as particularly challenging. Today, achieving yields over several grams per liters is regularly possible and thus overcomes the economic issues associated with the use of mammalian cell lines. These new advances in protein expression were encouraged by the fast increase of approved biotherapeutics expressed in mammalian cells.

More and more investments are made to develop biopharmaceuticals such as therapeutic antibodies or proteins. In this context, the use of mammalian cells for protein production is of particular interest.

The main difference between bacterial and mammalian cell lines comes from the presence of post-translational metabolic machinery. Thus, obtaining protein expression with proper glycosylation profiles is only possible with protein production in mammalian cells. This is particularly relevant for recombinant therapeutic antibody production where proper glycosylation can induce increased efficacy, stability and safety. In contrast, antibody fragments can be produced in bacterial expression systems.

Mammalian cells protein expression also allows for proper protein folding, a determining criteria to prevent the loss of biological activity.

To conclude, one of the main ideas to keep in mind is that recombinant protein expression in mammalian cells increases their compatibility for further human use. That’s why they are the reference expression systems when it comes to therapeutic antibody or protein production.