Vector Maps

FLAG® and 3xFLAG® Overview

A Proven System for Detection and Purification of Proteins
The FLAG Expression System is an established way to express, purify and detect recombinant fusion proteins. FLAG and 3xFLAG have proven utility in numerous applications such as Western blotting, immunocytochemistry, immunoprecipitation, flow cytometry, protein purification, and in the study of protein-protein interactions, cell ultrastructure and protein localization. These small hydrophilic tags facilitate superior detection and purification of recombinant fusion proteins when using our highly specific and sensitive ANTI-FLAG® antibodies.

Ideal Epitope Tags: Small, Hydrophilic and Cleavable
The FLAG expression system utilizes a short, hydrophilic 8-amino acid peptide that is fused to the recombinant protein of interest. Because of its hydrophilic nature, the FLAG peptide is likely to be located on the surface of the fusion protein. As a result, the FLAG peptide is easily accessible for cleavage by enterokinase (Ek) and for detection with antibodies. In addition, because of the small size of the FLAG peptide tag, it is not likely to obscure other epitopes, domains, or alter function, secretion, or transport of the fusion protein.

The 3xFLAG system is an improvement upon the original system by fusing 3 tandem FLAG epitopes (22 amino acids). Detection of fusion proteins containing 3xFLAG is enhanced up to 200 times more than any other system. Like the original FLAG tag, 3xFLAG is hydrophilic, contains an Ek cleavage site, and is relatively small. Therefore, the risk of altering protein function, blocking other epitopes or decreasing solubility is minimized.

How to use the table
The table below contains a list of available kits, each of which contains both a FLAG expression vector and control vector. For example, in the first row, Sigma® Product No. E6783 is a kit that contains a FLAG expression vector (Sigma Product No. E8770) and control vector (Sigma Product No. C3972). Vector sequences are available by clicking any of the Sigma product codes listed in the columns labeled "Expression Vector Sequence" and "Control Vector Sequence." Click on the vector diagram link to view a map of the corresponding expression vector. These maps are available as a downloadable PDF. It's best to change the page scaling option to "fit to printable area" for best results when printing.

back to top