Analysis on Cloning and Cequence Characteristics of Metallothionein Gene in Dard Clam Meretrix meretrix

Metallothioneins(MT)are low molecular weight,cysteine-rich,inducible metal-binding proteins found in a variety of organisms.MTs have many important biological functions acted as a protective role against excess reactive heavy metal ions,free radical scavengers and reservoir of essential metals that can be donated to other metalloproteins.The full-length cDNA sequence of metallothionein(named as Mm-MT)gene in the hard clam(Meretrix meretrix)was identified from M.meretrix cDNA library using expressed sequence tag(EST)method.The full-length cDNA of Mm-MT is of 657 bp and an open reading frame(ORF)of 231 bp encoding a polypeptide of 76 amino acids.The contents of cys in the Mm-MT amino acid sequence is 27.6%.Mm-MT is characterized by the conserved features of invertebrate’s MTs.The result of sequence analysis indicates that Mm-MT is the member of metallothionein family.This research will provide basic information for evolution and function study of marine shellshef metallothionein.