Cathepsin L protease belongs to the papain-like cysteine proteases family, plays indispensable roles in animals' pathological and physiological processes. However, little is known about Cathepsin L in silkworm, Bombyx mori. Herein, a novel Cathepsin L-like (Cat L-like) was cloned and identified from silkworm by the rapid amplification of cDNA ends (RACE). Cat L-like contains an intact open reading frame (ORF) of 1 668 bp and encodes 556 amino acid residues, consisting of a signal peptide, typical cathepsins’ inhibitor_I29, and pept_C1 domain. Cat L-like is specifically and highly expressed in hemocytes. The cathepsin (including Cathepsin L, B, and H) crude extract from hemocytes had typical substrate specific catalytic activities and were sensitive to pH and temperature. Cat L-like up-regulated considerably after 20-hydroxyecdysone (20-E) administration, indicating that Cat L-like may be regulated by insect hormone. The responses of Cat L-like against bacterial infection suggest it may play essential roles in silkworm immunity. Overall, our studies provide a theoretical basis and insights to further investigate the functions of Cat L-like and in insects' innate immunity mechanisms.

组织蛋白酶L蛋白酶属于木瓜蛋白酶样半胱氨酸蛋白酶家族，在动物的病理和生理过程中起着不可或缺的作用。然而，关于家蚕中的组织蛋白酶L知之甚少。本文中，通过快速扩增cDNA末端（RACE），从家蚕克隆并鉴定了新的组织蛋白酶L-样（Cat L- like）。Cat L- like包含1668 bp的完整开放阅读框（ORF），编码556个氨基酸残基，由信号肽，典型的组织蛋白酶抑制剂I29和pept_C1结构域组成。像猫L一样在血细胞中特异性和高度表达。来自血细胞的组织蛋白酶（包括组织蛋白酶L，B和H）的粗提物具有典型的底物特异性催化活性，并且对pH和温度敏感。猫L-像上调后20-羟基（20-E）给药相当，表明猫L-像可以通过昆虫激素来调节。的答复猫L-一样对抗细菌感染暗示它可能在家蚕免疫中发挥重要作用。总体而言，我们的研究为进一步研究Cat L- like的功能提供了理论基础和见解。 以及昆虫的先天免疫机制。