Precision Tagging: A Novel Seamless Protein Tagging by Combinational Use of Type II and Type IIS Restriction Endonucleases.

Protein tagging is a powerful tool for performing comprehensive analyses of the biological functions of a protein of interest owing to the existence of a wide variety of tags. It becomes indispensable in some cases, such as in tracking protein dynamics in a live cell or adding a peptide epitope due to the lack of optimal antibodies. However, efficiently integrating an array of tags into the gene of interest remains a challenge. Traditional DNA recombinant technology based on type II restriction endonucleases renders protein tagging tedious and inefficient as well as the introduction of an unwanted junction sequence. In our attempt to tag Thrombospondin type 1 domain-containing 1 (THSD1) that we identified as the first intracranial aneurysm gene (Santiago-Sim et al., 2016), we developed a novel precision tagging technique by combinational use of type II and IIS restriction endonucleases (Xu et al., 2017), which generates a seamless clone with high efficiency. Here, we describe a protocol that not only provides a generalized strategy for any gene of interest but also takes its application of 11 different tags in THSD1 as a step-by-step example.