Conduct a test based on the unique differences in the protein separate from other proteins. This test is called an "Assay" and it is necessary to use when finding the specific protein.
Separate the different structures of the cell to obtain the structure that has the highest concentration of your particular protein.
Decrease the density of the protein to help narrow your search for the exact protein you are looking for. Proteins all vary in density. Develop a homogenate by tearing the cell membrane by centrifugation. The least dense material, which is furthest from the bottom of the centrifuge tube, is called the "supernatant" and must be obtained and put into the centrifuge again---but at a much faster speed. This, in turn, creates a new supernatant. The repetitive process of putting the supernatant in the centrifuge is called differential centrifugation.
Add salt to the protein. This identifies different levels of solubility, allowing you to isolate the different subunits and structures.
Use different types of chromatography to further isolate the highest concentration of the protein. (See Resources.)
Use an SDS-PAGE analysis to figure out how accurate your protein purification plan was.