Method for fusion expression of ion channel protein and transport protein and protein fragment adopted by method

The invention provides a protein fragment for fusion expression of ion channel protein and transport protein. The protein fragment is characterized in that the protein fragment is a Bril protein fragment or protein of which the sequence homology with the fragment is more than 90%; or, the protein fragment is a T4L protein fragment or the protein of which the sequence homology with the fragment is more than 90%. According to the protein fragment provided by the invention, a fusion protein expression plasmid is also constructed by trying to insert fusion protein fragments such as BRIL and T4L into an N-terminal, a C-terminal or a membrane inner ring area of the ion channel protein and transport protein so as to improve the in-vitro stability and crystallizability. The ion channel protein and transport protein which have good stability and high expression quantity and can be crystallized can be successfully obtained.