Abstract: Utilizing technique of RT-PCR and sequencing, the nucleotide and deduced amino acid sequence of the porcine cystatin B (CSTB) gene were obtained in this study. The open reading frames (ORFs) of the CSTB gene were 294bp long (encoding for 98 amino acids). The nucleotide sequence identities of porcine CSTB Complete Coding Sequence (CDS) were 81%, 85% and 89% compare to that of the human, rat, and bovine CSTB CDS respectively. The deduced amino acid sequence identities of the porcine CSTB protein were 83%, 76%, and 85% compare to that of the rat, human, and bovine CSTB proteins, respectively. The structure of CSTB protein was predicted by homologous modelling which was similar to the results observed previously in humans and mouse. The five-stranded antiparallel β-sheet and the wedge shaped edge were found in the structure model. The polymorphisms of porcine CSTB gene was detected in 84 pigs by PCR-RFLP. Base on the polymorphism detection, the influence of CSTB genotype on tenderness traits were analyzed. The genotype AA in CSTB gene PvuII locus had significantly lower Shear force (5.11 kg), Toughness (19.31 kg.s) and Mean Shear force (3.26 kg) than genotype AB and BB (P<0.01).

Key words: pigs, cystatin B gene, gene cloning, tenderness