FLAG-tags are commonly used for protein abundance measurements and for identification of protein-protein interactions in living cells. We have observed that the cholera pathogen Vibrio cholerae encodes a FLAG-antibody-reactive protein and identified this protein as an outer membrane porin, Porin4, which contains a sequence very similar to the 3xFLAG epitope tag. We have demonstrated the binding affinity of the conserved peptide sequence (called Porin 4 tag) in Porin4 against monoclonal anti-FLAG M2 antibody. In addition, we created a porin4 deletion mutant, which can be used for background-less FLAG antibody detection experiments.

FLAG 标签通常用于蛋白质丰度测量和活细胞中蛋白质-蛋白质相互作用的鉴定。我们观察到霍乱病原体霍乱弧菌编码 FLAG 抗体反应蛋白，并将该蛋白鉴定为外膜孔蛋白 Porin4，其中包含与 3xFLAG 表位标签非常相似的序列。我们已经证明了 Porin4 中保守肽序列（称为 Porin 4 标签）对单克隆抗 FLAG M2 抗体的结合亲和力。此外，我们创建了一个porin4缺失突变体，可用于无背景 FLAG 抗体检测实验。