An expression system for a recombinant target protein in a host cell, comprising a nucleic acid segment consisting essentially of a nucleotide sequence coding for a protein transduction domain of SEQ ID No: 1, a nucleotide sequence coding for a Hsp40-J domain, and a nucleotide sequence coding for a target protein, wherein the nucleic acid segment is operatively linked to host specific transcription and translation regulatory elements for expressing the recombinant target protein in the host cell is provided. The invention also provides a method for producing a recombinant target protein with an enhanced yield in the host cell.
