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Recombinant DNA technology enables the insertion of specific foreign sequences to genes of interest. When these sequences encode short peptides they create an antigenic determinant (epitope) that can be recognized by antibodies. Thus, when the DNA sequence of interest is fused with the DNA sequence of the short peptide and introduced into cells, the resulting expressed protein is now a "tagged protein." Since antibodies to the peptide tag are commercially available, there is no need to generate specific antibodies to identify, immunoprecipitate or immunoaffinity purify the protein. Moreover, in most cases the stable fusion protein has the same bioactivity and biodistribution as the native protein.
Many different epitope tags have been engineered into recombinant proteins. These include FLAG™, HA, HIS, c-Myc, VSV-G, V5 and HSV.
| Tag
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Sequence
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| HIS |
HHHHHH |
| c-MYC |
EQKLISEEDL |
| HA |
YPYDVPDYA |
| VSV-G |
YTDIEMNRLGK |
| HSV |
QPELAPEDPED |
| V5 |
GKPIPNPLLGLDST |
| FLAG |
DYKDDDDK
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Due to the importance of this technology for protein expression, Sigma offers a wide range of products for the detection, isolation and purification of tagged proteins. These include monoclonal and polyclonals antibodies specific for the most commonly used epitope tags, as well as antibody-enzyme conjugates, fluorescent antibodies, antibody-affinity resins and the specific peptide tag sequence. Our products are carefully tested in many applications to ensure the most highly efficient performance.
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