Abstract: Three genes of paraoxonase (PON) family were separated from the liver of Xiang pig by reverse transcription polymerase chain reaction (RT-PCR) method. The cDNA of PON1, PON2 and PON3 were 1164, 1212 and 1080 base pairs in length, respectively. All of them contained complete open reading frame (ORF) coding for three precursors. The signal peptides were predicted to be 15 amino acids (aa) in PON1, 23 aa in PON2 and 23 aa in PON3 at the N-terminus of precursors. A nonsense mutation was found out from PON1 gene. Two changes in PON2 gene resulted in substitution from glutamine to arginine at 234 site (Q234R) and valine to isoleucine at 269 site (V269I) in the matured PON2 protein. In PON3, only one mutation lead to substitution from arginine to histidine at 127 site (R127H) of the matured protein. All of the three replacements in mature proteins might change the microenvironment in the internal proteins based on the prediction of the three dimension structures of the matured proteins online. It suggested that the differences of the three paraoxonase genes might correlate to the stress resistance of Xiang pig.

Key words: Xiang pig; paraoxonase; PONs gene family