What is a T7 tag and can if be used to purify synthesized proteins? Is it charge based like a His tag?


The T7 tag is the first 11 amino acids of the T7 gene 10 protein. Basically, if you engineer a protein with the T7 tag, you've engineered a small, known epitope to the protein of interest which may be detected immunologically. The small size of the epitope reduces the chance it will disrupt the protein's normal function (to which it's tagged). If we look at the affinity purification kit on the following product page we can see that specific vectors can be used to express T7-tagged proteins, and an immunoaffinity column can be used to purify the protein of interest. The T7 tag chemical structure is denoted here.

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    $\begingroup$ It also allows the discrimination of engineered protein from in vivo expressed proteins and you don't have to make specific antibodies for each protein but use antibodies against the t7 tag instead. $\endgroup$
    – Chris
    May 26 '15 at 19:44
  • $\begingroup$ What makes it different from the FLAG-Tag? (Besides sequence of course) $\endgroup$
    – user137
    Jun 25 '15 at 21:44
  • $\begingroup$ I don't have any data on how each epitope may affect stability or what have you, but it generally follows that whether it be T7, FLAG, HA or Myc etc. they're just method of recognition through the use of an anti-tag antibody (anti-HA, anti-FLAG, etc.) in immunoassay. $\endgroup$
    – CKM
    Jun 26 '15 at 17:40

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