CLONING OF A LOCUSTA CDNA-ENCODING A PRECURSOR PEPTIDE FOR 2 STRUCTURALLY RELATED PROTEINASE-INHIBITORS

Two peptides of respectively 35 and 36 residues were recently isolated from Locusta migratoria and their full structural characteristics wer e established by Edman degradation and mass spectrometry. These peptid es were subsequently shown to have a proteinase inhibiting activity. W e report here the cloning and characterization of a cDNA encoding a 92 -residue precursor with three distinct domains: (I) a typical signal p eptide of 19 residues; (II) the peptide sequence of the 35-residue inh ibitor separated by a Lys-Arg dipeptide cleavage site from (III) the p eptide sequence of the 36-residue inhibitor. We show by Northern blot analysis that the gene encoding this precursor is mainly transcribed i n the cells of the fat body.