The present invention relates to a process for the production of a heterologous polypeptide with homogeneous N-terminus in a bacterial host cell, wherein the heterologous polypeptide is autoproteolytically cleaved from an expressed fusion protein which comprises a polypeptide with the autoproteolytic activity of an autoprotease N.sup.pro of a pestivirus and the heterologous polypeptide by the N.sup.pro autoproteolytic activity.