Abstract: Disclosed is a method for producing a recombinant protein of interest which is characterised by the following steps: (a) providing a first part of an Npro autoprotease and providing a second part of an Npro autoprotease, wherein said second part is fused by a peptidic bond to a protein of interest but said second part alone does not exhibit a proteolytic activity, and wherein complementation of said first part with the second part forms an autoproteolytically active Npro autoprotease, (b) contacting the first part of the Npro autoprotease with the second part of the Npro autoprotease so that an autoproteolytically active Npro autoprotease is formed and the protein of interest fused by the peptidic bond to the second part of the Npro autoprotease is proteolytically cleaved off the second part of the Npro autoprotease at the peptidic bond, and (c) recovering the protein of interest.