Cellular Binder Trap Enrichment^®(cBTE)

cBTE is the first and only technology for screening of DELs inside a living cell. The advantage of screening inside a cell includes:

• Screening under physiologically relevant conditions
• Lower attrition rate
• No need for highly purified target protein
• Broader protein target space

Screening of DELs inside a cell, encompasses two fundamental challenges: 1) delivery of the DEL into the cell, and 2) discrimination between library members binding to the target protein and the endogenous cell proteins.

In cBTE, the fundamental challenges are resolved by 1) simple microinjection of the DEL into the cell, and 2) specific DNA labeling of the target protein, which provides the set-up for Binder Trap Enrichment (BTE).

cBTE uses the Xenopus laevis oocytes – widely used for the expression of heterologous proteins since the 1970s.

• 1 mm diameter
• 1 µL volume
• 100 000 times bigger than somatic cells
• 400 ng heterologous protein per day

Specific DNA labeling of the target protein is achieved by expressing the target protein fused to “prey”. Prey is a protein which binds “bait”. Bait is a small molecule. Bait is installed on DNA and delivered together with the DEL into the cell by microinjection.