Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources and College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China.
Dev Comp Immunol. 2013 Sep;41(1):94-9. doi: 10.1016/j.dci.2013.04.014. Epub 2013 Apr 28.
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.
组织蛋白酶 B 是一种溶酶体半胱氨酸蛋白酶，在脊椎动物中受到了广泛关注。然而，人们对贝类中的组织蛋白酶 B 的功能知之甚少。本研究在缢蛏（Sinonovacula constricta）中鉴定了组织蛋白酶 B 基因。该蛋白具有典型的半胱氨酸蛋白酶结构，包含 15 个残基的假定信号肽、75 个残基的前肽和 249 个残基的成熟结构域。在成熟结构域中，存在一个封闭环、一个氧阴离子穴（Gln）和一个催化三联体（Cys、His 和 Asn）。组织蛋白酶 B 基因在广泛的组织中表达，但在肝脏中表达水平最高。在早期发育阶段，可以广泛检测到转录本。在缢蛏感染鳗弧菌后，组织蛋白酶 B 基因的表达在感染后 8 小时在肝脏和套膜组织中表现出最显著的上调。细菌感染可以诱导组织蛋白酶 B 转录本的表达这一事实表明，组织蛋白酶 B 可能在贝类的先天免疫中发挥重要作用。
