CYSTEINE PROTEINASE-1 (CP1), A CATHEPSIN L-LIKE ENZYME EXPRESSED IN THE DROSOPHILA-MELANOGASTER HEMOCYTE CELL-LINE MBN-2

We have isolated cDNA clones encoding the full-length Drosophila melan ogaster cysteine proteinase 1 (CP1). The clones were isolated from the Drosophila melanogaster haemocytic mbn-2 cell line, where the gene is relatively strongly expressed, giving a transcript of 1.6 kb in size. We present the sequence encoding the full-length protein, and deduce the genomic organization of the gene by comparison to previously publi shed genomic partial sequence data. Immunofluorescence shows that CP1 is localized in small granules, probably lysosomes, in mbn-2 cells. Th e data presented suggest a role for cysteine proteinases in immune fun ctions in insects. it is likely to participate in the degradation of i nternalized material in phagocytic cells.