title: Identification of cathepsin B in the razor clam Sinonovacula constricta and its role in innate immune responses.
abstract: Cathepsin B, a lysosomal cysteine protease, has drawn much attention in vertebrates. However, very little is known about the functions of cathepsin B in bivalves. In this study, we identified the cathepsin B gene in the razor clam Sinonovacula constricta. The protein has a typical cysteine protease structure, comprising a 15-residue putative signal peptide, a 75-residue propeptide and a 249-residue mature domain. In the mature domain, there is an occluding loop, an oxyanion hole (Gln) and a catalytic triad (Cys, His and Asn). The cathepsin B gene is expressed in a wide range of tissues but appears to exhibit greatest level of expression in the liver. During the early developmental stages, the transcript could be detected widely. After the clam was infected with Vibrio anguillarum, the expression of the cathepsin B gene showed the most significant up-regulation in the liver and mantle tissues at 8h after infection. The fact that bacterial infection can induce the expression of the cathepsin B transcript suggests that cathepsin B could play an important role in the innate immunity of clams.
authors: Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources and College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China.
authors: Donghong
authors: D
authors: Niu
authors: Kai
authors: K
authors: Jin
authors: Lie
authors: L
authors: Wang
authors: Fanyue
authors: F
authors: Sun
authors: Jiale
authors: J
authors: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000201:enzymology / Q000276:immunology* / Q000821:virology; D002401:Cathepsin B / Q000145:classification / Q000235:genetics / Q000276:immunology*; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D008099:Liver / Q000201:enzymology / Q000276:immunology* / Q000821:virology; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014733:Vibrio / Q000276:immunology
chemical_list: D002401:Cathepsin B