Bioproduction Services- High Yield CHO Cell Lines

TARGATT™ for Bioproduction of Recombinant Proteins in Chinese Hamster Ovary (CHO) cells. The traditional CHO-cell based protein production is inefficient because it requires random insertion and forced amplification of transgenes.  ASC has “master” TARGATT™ CHO cell lines in two lineages to enable site-specific, single-copy insertion of large transgenes into a preselected safe harbor locus in the CHO cell genome, for high expression levels of your gene of interest. This site-specific TARGATT™ technology overcomes challenges posed by traditional insertion methods, and results in high integration efficiency (>90%), stable knock-in cell lines, uniform gene expression and reproducibility of clones. The Master TARGATT™ CHO cell lines are ideal for antibody and recombinant protein expression.

Products and Services
Application Notes

Antibody Production in a Custom TARGATT™ CHO-H11 cells


Figure 1. Expression of antibodies Ab1 and Ab2 in the H11 genomic hotspot locus of the TARGATT™ CHO-H11 cells yielded ~1g/L of each protein.

Optimizing Docking Site Location in TARGATT™ CHO-S Cell Lines


Figure 2. Expression of green fluorescent protein (GFP) in various genomic hotspot loci in TARGATT™ CHO-S cells. TARGATT™ CHO-S master cell lines were engineered with attP docking site in the well-characterized H11 locus and 4 different proprietary loci, ASC1, ASC2, ASC3, and ASC4. The GFP reporter gene was inserted into each cell line and its expression from each locus was measured using FACS analysis. Reporter expression in the ASC2 locus was 2.5-fold higher than the expression in the H11 locus. The estimated protein yield from the TARGATT™ CHOS-S-ASC2 Master cell line is ~2.5 g/L.

High Efficiency GFP Knock-in and Expression in TARGATT™ CHO-K1 Cells


Figure 3. GFP expression was measured by fluorescence imaging after transfection in parental CHO-K1 cell lines by random integration (A-B) and in TARGATT™ CHO-K1 Master Cell Line by site-specific gene integration (C-E). (A) CHO-K1 parental cell line without transfection; (B) CHO-K1 parental cell line randomly transfected with GFP plasmid; (C) CHO-K1 master cell line without transfection; (D) CHO-K1 master cell line transfected with GFP plasmid before GCV selection; (E) CHO-K1 master cell line transfected with GFP plasmid after GCV selection.

Technical Details

Licensing and Evaluation Programs Available!

ASC’s TARGATT™ technology improves CHO recombinant protein or antibody production capability by reducing cost and improving manufacturing feasibility for companies and projects of all sizes. Please let us know if you have questions about your CHO bioproduction project.


TARGATT™ Site-Specific Insertion

Traditional Random Gene Insertion

Safe Genomic Locus


No; random

Protein Yield



Gene Insertion Efficiency




Yes; for any protein

No; different from one protein to another

Copy # of Inserted Gene

Single copy

Multiple copies



No; Chromosome rearrangement

Gene Silencing



Advantages of using TARGATT™ Master Cell Lines for gene knock-in:

  • Stable cell line generation
  • Single copy, site-specific gene integration into the safe harbor locus
  • Guaranteed gene expression from an active, intergenic locus
  • Footprint-free integration of gene of interest
  • Use of selection marker is not necessary but optional
  • Easy-to-use protocol requiring transfection of only one (donor) plasmid

Key points:

  • Ablility to achieve > 1 g/l antibody bioproduction using a single site insertion with little optimization
  • Identification of the ASC-X locus has allowed for a further, > 2.5-fold increase in protein expression levels 

TARGATT™ Technology Applications:


TARGATT™ CHO and HEK293 Master Cell Lines

  • Chi, X., Zheng, Q., Jiang, R., Chen-Tsai, R. Y., & Kong, L. J. (2019). A system for site-specific integration of transgenes in mammalian cells. PLOS ONE14(7), e0219842.
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