Soluble glutathione S-transferase (sGST) is extremely important for metabolic detoxication by catalyzing the conjugation of GSH (glutathione) with microcystins.In this study,the amino acid sequence of a mu-class sGST cDNA fragment from the liver of Macrobrachium nipponensis were firstly obtained by RT-PCR using degenerated primers.Sequence analysis revealed that the cloned mu-class sGST cDNA fragment was 299 bp in length,encoding 99 amino acids.Homologous analysis showed that the nucleotide sequence of the glutathione S-transferase gene in M.nipponensis was 60% homologus to the glutathione S-transferase gene of Litopenaeus vannamei,Rattus norvegicus,Mus musculus,Ixodes scapularis,Rhipicephalus appendiculatus,Xenopus tropicalis,Rhipicephalus microplus and Crassostrea gigas.This suggested that the sGST cloned in this study belonged to mu-class GST.The result of further experiment showed that mu-class sGST level did not change significantly in M.nipponensis exposed in MC-LR.