Cloning, Expression and Characterization of Translationally Controlled Tumor Protein （TCTP） Gene from Flatfish Turbot （Scophthalmus maximus）

A full-length cDNA encoding translationally controlled tumor protein of marine flatfish turbot (Scophthalmus maximus), SmTCTP, was isolated with rapid amplification of cDNA Ends (RACE). SmTCTP consisted of a 5' untranslated region (UTR) of 84 bp, a 3' UTR of 451 bp and an open reading flame (ORF) of 513 bp, encoding a protein of 170 amino acid residues, which contained two signature sequences of TCTP family. The 5'UTR of SmTCTP started with a 5'-terminal oligopyrimidine tract (5'-TOP), a typical feature for translationaily controlled mRNAs. The deduced amino acid sequence of SmTCTP was similar to the other known verte-brate TCTPs in a range of 58.8% to 64.1%. The length offish TCTPs was diverse among species, e.g., TCTP of turbot and sea perch (Lateolabrax japonicus) is 170 aa in length, while that of zebrafish (Danio rer/o) and rohu (Labeo rohita) is 171 aa in length. North-ern blot analysis revealed that SmTCTP has only one type of mRNA. Its expression level in albino skin was slightly higher than that in normal skin. We constructed the pET3Oa-SmTCTP expression plasmid. The recombinant protein of His-tag SmTCTP was over-expressed in E. coli, purified and identified with peptide mass fingerprinting. These results may pave the way of further inves-tigation of the biological function of TCTP in fish.