A research group led by Prof. Kenji Miura (University of Tsukuba) and Prof. Yukinari Kato has demonstrated that the RAP tag, developed to label target proteins produced in animal cells, is also effective for detecting proteins produced in plant cells. Furthermore, they have shown that the PMab-2 antibody, which recognizes the RAP tag, can be efficiently produced in plants, making it useful for purifying tagged proteins.
To investigate the function and localization of a target protein among the many types of proteins present in living organisms, antibodies specific to that target protein are required. However, these are not always readily available. Therefore, by using genetic engineering techniques to attach a marker tag to the target protein and express it within the organism, it can be distinguished from other proteins. Nevertheless, difficulties such as tag antibodies failing to function specifically when expressed in plants have limited practical applications to only a few types thus far.
In this study, we demonstrated that when RAP-tagged proteins are expressed in plants, the target protein can be specifically detected using the PMab-2 antibody. Furthermore, we showed that the target protein can be purified using affinity chromatography with the PMab-2 antibody. Furthermore, using the “Tsukuba System” developed by our research group, we successfully produced large quantities of the PMab-2 antibody that recognizes the RAP tag in plant cells. This plant-derived PMab-2 antibody can be purified simply and with high purity, and it was shown to possess antibody activity equivalent to that of the CHO cell-derived PMab-2 antibody.
These findings demonstrate that the RAP tag functions effectively in plants and that the “Tsukuba System” enables the production and purification of the PMab-2 antibody that recognizes the RAP tag, adding a new repertoire to tag systems in plants. This is expected to contribute to establishing foundational technology for low-cost antibody production and purification, and further to the advancement of plant biotechnology.
The results were published in Frontiers in Plant Science on September 10, 2020.
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