MOLECULAR-CLONING AND SEQUENCING OF 2 CDNAS ENCODING CATHEPSIN L-RELATED CYSTEINE PROTEINASES IN THE NERVOUS-SYSTEM AND IN THE STOMACH OF THE NORWAY LOBSTER (NEPHROPS-NORVEGICUS)

Two cathepsin L-related cysteine proteinase molecular clones were isol ated from cDNA libraries of mRNA from the eyestalk nervous system and the stomach of Nephrops norvegicus and sequenced. The cDNA from nervou s system was first obtained by screening an eyestalk cDNA library with an oligonucleotide whose sequence derived from the amino acid sequenc e of a peptide isolated previously and subsequently with the 5' end of the longest cDNA probe thus obtained. Several clones were isolated an d analysed: one of these clones contains the complete cDNA (NCP1: AC = X80989). It encodes a preproenzyme of 324 amino acid residues, and a putative mature enzyme of 217 residues. Only one variant (with one ami no acid change) was identified. The screening of the stomach cDNA libr ary was carried out with a cDNA probe corresponding to the 5' terminal region of the nervous system cysteine proteinase cDNA previously obta ined, A near full-length cDNA (NCP2: AC = X80990) was isolated. The se quence for mature stomach cathepsin L-related cysteine proteinase is 2 15 residues long. Nervous system cathepsin L-like NCP1 is very similar to the American lobster cysteine proteinase LCP1 (81% identity) and t he stomach cathepsin L-related NCP2 is very similar to cysteine protea se LCP3 (82% identity). Moreover, comparison of the two Nephrops norve gicus cathepsin L-related cysteine proteinases revealed only 68% ident ity.