Ee3 family proteins and corresponding DNA sequences.

Nucleic acid, characterized in that it encodes a polypeptide according to one of Figures 13 or 15A, or variants thereof, having in the plane of amino acids at least 90% identity to a polypeptide according to one of the figures 13 or 15A, except a nucleic acid according to SEQ ID NO: 75 of WO01 / 98353.