| abstract |
Provided is a polypeptide tag. The amino acid sequence of the polypeptide tag is Xaa1Xaa2Xaa3PHDYNXaa4Xaa5Xaa6, wherein in the formula, Xaa1, Xaa2, Xaa3, Xaa4, Xaa5, and Xaa6 are each independently an amino acid or none. The polypeptide tag is used for labeling a target protein. In a second aspect, provided is a polypeptide fusion protein, comprising the following two structures: (1) any polypeptide tag according to the first aspect, and (2) a target protein connected to the polypeptide tag. Also provided are an in vitro cell-free protein synthesis system and an application thereof in in vitro protein synthesis. By constructing the polypeptide tag and a target protein as a fusion protein, the expression of the labeled target protein can be effectively increased without removing the polypeptide tag. |