Molecular cloning and mRNA expression of the liver-specific cathepsin L1 gene of the olive flounder, Paralichthys olivaceus.

We isolated a homolog of cathepsin L from a cDNA library of the olive flounder liver. The flounder cathepsin L1 transcript consisted of 1,221 bp that encoded a polypeptide of 334 amino acids. The overall identity between flounder cathepsin L1 and other cathepsin Ls was 50-64%, and flounder cathepsin L1 contained the highly conserved ERFNIN-motif. A phylogenetic tree indicated that flounder cathepsin L1 is in the same monophyletic group as zebrafish cathepsin Lc. RT-PCR analysis revealed that cathepsin L1 transcripts were expressed only in the liver. They were detected from 28 d post-hatching. Under starvation conditions, cathepsin L1 expression was decreased at 30 d.