Application list of expression system 

Overview of mammalian cell expression

Protein will have the function of folding and post-translational modification, bringing the protein closer to the native protein, thereby obtaining the same biological activity as the native protein.

Therefore, the mammalian cell expression system has the most extensive application in the development and production of recombinant protein drugs, especially therapeutic recombinant monoclonal antibodies.

Mammals are eukaryotic cells, and the organelle can fold proteins correctly.

Vectors can express recombinant proteins in mammalian cells with expressions up to 1-3 g/L

Efficient promoter control, stable expression, and a variety of expression system options: instantaneous expression, stable cell line expression, nutritional defect cell line expression (DHFR/GS), large-scale suspended cell expression, etc.

The most commonly used mammalian expression host cells (HEK293 and CHO) can be used to culture suspended cells produced within a month number of grams protein. 

Leading Biology mammalian cell expression system

Leading Biology provides one-step protein technical services, such as expression vector construction, transient transfection, expression testing, large-scale animal cell fermentation and protein purification.

Expression vectors: common vectors pcDNA 3.1, pIRES, pTT3, pCEP4, pATX, etc. as well as our own patent vectors.

Leading Biology mammalian cell expression service

1. Vector construction and optimization

   1). cDNA can be cloned into the  mammalian cell expression vector provided either by customers or by Leading biology;

   2). The secretory signal peptide and purification tag can be added to the expression vector to promote the secretion expression of target protein and meet the needs of one-step affinity purification;

   3). Can produce and identify high efficiency and stable cell lines, which is suitable for large-scale fermentation.

2. Stable gene expression cells meet the needs of  long-term survival

The entire experimental process provides long-term stable and adjustable protein production.

3. Transient expression (TGE)

   1). Compared with the stable gene expression, TGE is mainly used for the preparation of recombinant protein in the short term. It can be transfected rapidly in 10 days without the genetic selection of the plasmid DNA;

   2). We using suspension cells for the instantaneous expression process, this method could achieve large-scale protein expression (-100L).

4. Process development and scale expansion

Leading biology is able to optimize the expression procedure and expression product, detection of cell expression, looking for the optimize fermenting condition, which is suitable for large-scale fermentation.

5.Purification

 Leading biology has a complete protein purification system, have affinity purification, gel filtration, ion exchange and hydrophobicity chromatography purification methods. This system could fulfill protein purification both with or without tag and optimize the purification process.

Service Process

Classic case

A biologic organelles matrix protein

Full length  334aa, 

Weight 37.03kDa,  Fc tag protein, 

293F cell expression. 

After the coding gene whole codon optimization, it was constructed on a pTT3 vector, sequencing verification followed by 30mL test expression (Fig.1).

Figure 1. Expression result (Coomassie blue staining)

MW. Molecular weight marker. Ø. Non-transfected (negative control).

To get the maximum recovery of target protein, we did Protein G purification twice to the flow-through (Fig.2, Fig. 3), the remaining target protein in FT can be observed after the second purification.

                      Figure 2. Target protein purification profile.                                         Figure 3. Target protein purification profile. Reducing-PAGE analysis.

Therefore, we raised the salt concentration to 300mM, after elution, the amount of the remaining protein in FT decreased significantly (Fig. 4).

Figure 4. Target protein purification profile. Coomassie blue staining.Reducing-PAGE analysis.

After experimental conditions optimization, we do large-scale expression, using 2L fermentation.

Figure 5. Target protein purification profile and QC gel.

Related Services

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Protein Expression in Mammalian Cells

Protein Expression in Baculovirus

Protein Expression in Yeast

Protein Expression in Bacillus subtilis

Protein Expression in E coli

Virus-like particles/Phage library expression system based

Cell-free expression system

Whole cell-based protein expression system

Why Leading Biology?

At Leading Biology, we custom protein purification design for every single protein to ensure the production and recovery rate as high as possible.

Working with us, you will get stability, and it means a reliable partner to help streamline your R&D process.

Working with us, you will get the guaranteed service to accommodate your requirements.

• Innovative configurations of chromatography columns custom tailored to each protein
• Vigorous quality control system to ensure the required quality and reproducibility
• Production capacity of up to tens of grams
• Flexible scale-up protein production
• Competitive price with fast turnaround time

Contact Information

Please obtain a quote before ordering, and refer to the quote number when you place an order.

Orders are typically confirmed within 12 hours.

Have a Question? Email us info@leadingbiology.com

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By Phone: 1-661-524(LBI)-0262 (USA)