Detection of protein translocation by beta-galactosidase reporter fragment complementation

A method to assess intracellular translocation of a mammalian protein of interest in a cell, comprising:

• (a) expressing in said cell a first fusion protein of the mammalian protein of interest fused to a β galactosidase peptide alpha fragment having an amino acid sequence according to wild-type SEQ ID NO:
• 1, provided that said sequence comprises a mutation changing one amino acid in said sequence between residues H31 and E41, or a truncation as shown in SEQ ID NO:
• 6;
• (b) expressing in said cell a second protein fused to a β galactosidase peptide fragment that can complement said alpha fragment to form an active β galactosidase enzyme that generates a detectable signal when said first fusion protein is translocated to allow complexing with said second fusion protein;
• and
• (c) detecting said signal produced by said active complex in said cell to assess intracellular translocation of said mammalian protein of interest.