A use of a signal peptide for producing a recombinant polypeptide of interest in an expression system, the signal peptide includes at least 12 amino acids of formula (I):(X1)iX2X3X4SX5X6X7,wherein:X1 is a peptide containing from 3 to 6 amino acids, i equal to 0 or 1,X2 is a peptide containing from 3 to 9 hydrophobic amino acids,X3 is a peptide containing from 3 to 5 amino acids, the peptide including at least 3 contiguous or non-contiguous leucinesX4 is a peptide containing from 2 to 5 amino acids chosen from Ala, Thr, Ser, Gln, Ile, Met,X5 is Ala or Val,X6 is Gln, Asn or His,X7 is Ala or Cys,provided that when the signal peptide originates from a natural precursor of a specific protein, the polypeptide of interest is different from the protein.
