Mammalian Cell Expression

Proteos provides expression of recombinant proteins and antibodies in mammalian cells that include appropriate post-translational modifications.  These post-translational modifications are often required for efficient secretion and function, which is why mammalian cell production is preferred in cases that require biologically functional proteins.

Our industry leading transient expression platform utilizes fully licensed HEK (human embryonic kidney) and CHO (Chinese hamster ovary) cells lines expressing the Epstein-Barr virus (EBV) nuclear antigen 1, with proprietary expression vectors containing the EBV origin of replication (OriP) to allow episomal plasmid amplification and high-level recombinant protein expression.

We also offer cell line expansion, banking, and transient expression in client-provided cell lines.

Our optimized and fully validated mammalian cell expression protocols provide consistent, reproducible protein expression in serum-free shake flask culture volumes ranging from 30 mL to 60 L per batch.   Only mycoplasma-free, high viability, low passage cultures are used for transfection and are monitored using a Beckman Coulter Vi-CELL XR for culture density, viability, and average cell diameter.  The Vi-CELL XR uses the trypan blue dye exclusion method and averages 50 measurements to compute the parameters for each sample.  This allows us to monitor cultures with a high degree of accuracy which is imperative for quality and reproducibility of protein production projects.  All cell culture data is included in a customized technical report delivered with each project.

Typical productions times are 6-8 weeks from construct design to purified protein.

Services include:

  • Full suite of molecular biology services to accompany any of our expression platforms, including construct design, fusion partner and affinity tag selection, gene synthesis with codon optimization, subcloning, endotoxin-free plasmid DNA isolation, and sequence verification.
  • Expression verification and optimization at culture scales less than 100 mL; ideal for expression testing of multiple recombinant protein targets in parallel.
  • Pilot scale production and yield determination at culture scales ranging from 1 L to 4 L; ideal for process verification through purification prior to large-scale production.
  • Preparative scale production of recombinant proteins in HEK or CHO cells in shake flask culture volumes up to a 60 L batch size.
  • Options for delivery include cell paste, conditioned culture supernatant, concentrated buffer-exchanged culture supernatant, or membrane preparations.
  • Mammalian cell expression services can be combined with Proteos’ purification services for a fully-customized protein production process.
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