Designed by: Lena Schorr   Group: iGEM19_FAU_Erlangen   (2019-10-18)

scFv bispecific antibody against GPA33 and CD3 codon optimized for E.coli

The composite part BBa_K3117029 is a bispecific antibody targeting GPA33 and CD3. It can be used to direct T lymphocytes to colon carcinoma cells by binding CD3 on T-cells and GPA33 on colon carcinoma cells. This part is codon optimized for the expression in E.coli.

Usage and Biology

The part consists of humanized anti-CD3 and anti-GPA33 single-chain variable fragments (scFv) (BBa_K3117033, BBa_K3117035, BBa_K3117034, BBa_K3117046), which are connected by a flexible (GGGGS)4 linker (BBa_K3117004). The scFvs are formed by the variable regions of the heavy and light chain of the respective antibodies that are connected by either a (GGGGS)4 or (GGGGS)3 linker (BBa_K3117004, BBa_K3117028). The sequence contains a C-terminal His-Tag (BBa_K3117005) for easy purification and detection. Secretion of the protein into the periplasm is ensured by a pelB sequence (BBa_K3117012).

T lymphocytes are part of the adaptive immune system and perform a wide variety of functions. Among these are the identification and the subsequent destruction of aberrant, e.g. cancerous, cells. Antibodies that target the T cell marker CD3 have been shown to be sufficient for activation of the lymphocytes. Which makes them an attractive tool for research and clinic, especially for cancer therapy (Ellerman, 2019). By targeting GPA33, expressed on over 95% of colon cancer cells (Rageul et al., 2009), our part is meant to link T cells with colon cancer cells and simultaneously activate them, so that the cancer cells are killed.


1. Ellerman, D. (2019). Bispecific T-cell engagers: Towards understanding variables influencing the in vitro potency and tumor selectivity and their modulation to enhance their efficacy and safety. Methods, 154, 102-117.

2. Rageul, J., Mottier, S., Jarry, A., Shah, Y., Théoleyre, S., Masson, D., . . . Denis, M. G. (2009). KLF4‐dependent, PPARγ‐induced expression of GPA33 in colon cancer cell lines. International journal of cancer, 125(12), 2802-2809.