Aquatic Molecular Biology Lab Centro de Investigacion en Alimentacion y Desarrollo (CIAD), A. C. Carretera a Ejido La Victoria Km 0.6. PO Box. 1735, Hermosillo, Sonora, 83000, Mexico.
Comp Biochem Physiol B Biochem Mol Biol. 2012 Jan;161(1):32-40. doi: 10.1016/j.cbpb.2011.09.004. Epub 2011 Sep 16.
Cathepsin B is a cystein proteinase scarcely studied in crustaceans. Its function has not been clearly described in shrimp species belonging to the sub-order Dendrobranchiata, which includes the white shrimp Litopenaeus vannamei and other species from the Penaeidae family. Studies on vertebrates suggest that these lysosomal enzymes intracellularly hydrolize protein, as other cystein proteinases. However, the expression of the gene encoding the shrimp cathepsin B in the midgut gland was affected by starvation in a similar way as other digestive proteinases which extracellularly hydrolyze food protein. In this study the white shrimp L. vannamei cathepsin B (LvCathB) cDNA was sequenced, and characterized. Its gene expression was evaluated in various shrimp tissues, and changes in the mRNA amounts were compared with those observed on other digestive proteinases from the midgut gland during starvation. By using qRT-PCR it was found that LvCathB is expressed in most shrimp tissues except in pleopods and eye stalk. Changes on LvCathB mRNA during starvation suggest that the enzyme participates during intracellular protein hydrolysis but also, after food ingestion, it participates in hydrolyzing food proteins extracellularly as confirmed by the high activity levels we found in the gastric juice and midgut gland of the white shrimp.
组织蛋白酶 B 是一种半胱氨酸蛋白水解酶，在甲壳类动物中研究甚少。其功能在属于枝鳃亚目（Dendrobranchiata）的虾类中尚未明确描述，该亚目包括凡纳滨对虾（Litopenaeus vannamei）和其他对虾科（Penaeidae）的物种。对脊椎动物的研究表明，这些溶酶体酶在细胞内水解蛋白质，与其他半胱氨酸蛋白水解酶一样。然而，在白虾 L. vannamei 中，编码虾组织蛋白酶 B 的基因在中肠腺中的表达受饥饿的影响与其他在细胞外水解食物蛋白的消化蛋白酶相似。在这项研究中，我们对凡纳滨对虾的组织蛋白酶 B (LvCathB) cDNA 进行了测序和表征。评估了其在各种虾组织中的基因表达，并将其与饥饿期间从中肠腺中观察到的其他消化蛋白酶的 mRNA 量变化进行了比较。通过使用 qRT-PCR 发现，LvCathB 在大多数虾组织中表达，除了在步足和眼柄中不表达。在饥饿过程中 LvCathB mRNA 的变化表明，该酶参与细胞内蛋白质水解，但也参与食物蛋白的细胞外水解，这从我们在白虾胃液和中肠腺中发现的高活性水平得到了证实。
