Amino acid sequence of honeybee prepromelittin synthesized in vitro.

Translation of melittin messenger RNA from queen bee venom glands in a cell-free system from wheat germ yielded prepromelittin. Sequence analysis of the labeled in vitro product was performed by automatic Edman degradation of the intact polypeptide as well as by analysis of some of its proteolytic fragments. Prepromelittin was shown to be composed of 70 amino acids, two of which have not been identified. The sequence of melittin is located in the COOH-terminal third of the polypeptide chain (residues 44--69). Prepromelittin starts with a very hydrophobic pre-region, probably 21 residues long, followed by a pro-part of unusual sequence, containing only alanine, proline, and acidic residues. At least three post-translational reactions are required to convert prepromelittin to mellitin.