Molecular cloning and characterization of cathepsin F gene from olive flounder Paralichthys Olivaceus

We isolated a homologue of cathepsin F from cDNA library of olive flounder liver. A 2,077 kb full-length cDNA encoding a predicted polypeptide of 474 amino acids was sequenced. The flounder cathepsin F exhibits a domain structure typical for papain-like cysteine proteases, a 17 amino acid N-terminal hydrophobic signal sequence followed by an extraordinarily long propeptide of 244 amino acids and the domain of the mature protease comprising 213 amino acids. The mature region contains all features characteristic of a papain-like cysteine protease, including the highly conserved cysteine, histidine and asparagine residues of the ‘catalytic triad’. The cathepsin F protein showed 49–99% amino acid sequence identity with other known cathepsin F sequences. An in vivo expression study showed that cathepsin F mRNA was expressed predominantly in brain, liver, eye and heart, and moderately in other tissues. The accumulation of cathepsin F mRNA in early stage of development increased with development. This expression pattern suggests that flounder cathepsin F has been implicated in the growth and reproduction regulation.