Cytochrome b₅ (Cyt-b₅) is a small heme protein and known to be involved in a wide range of biochemical transformations, including cytochrome P450 monooxygenase (CYP)-mediated metabolism of endogenous and exogenous compounds. Studies on Cyt-b₅ are more concentrated in mammals, but are relatively rare in insects. The characteristics and function of Cyt-b₅ from Locusta migratoria have not been described yet. We sequenced the full-length cDNA sequence of Cyt-b₅ from L. migratoria (LmCyt-b₅) by reverse transcription-PCR (RT-PCR) based on locust transcriptome database. The phylogenetic analysis showed that LmCyt-b₅ was closely related to the Cyt-b₅ from Blattodea. LmCyt-b₅ was highly expressed in ovary, Malpighian tubules, midgut, gastric caeca, and fat bodies. Silencing of LmCyt-b₅ had no effect on the susceptibility of L. migratoria to four different insecticides. Suppression of LmCyt-b₅ or silencing of both LmCyt-b₅ and LmCPR did not significantly change the total CYP activity toward the substrate 7-ethoxycoumarin (7-EC). However, coexpression of LmCYP6FD1 with LmCPR and LmCyt-b₅ together in Sf9 cells by using Bac-to-Bac baculovirus expression system significantly increased the catalytic activity of LmCYP6FD1 toward 7-EC as compared with the coexpression of LmCYP6FD1 with cytochrome P450 reductase (LmCPR) or LmCyt-b₅ separately. These results suggest that LmCyt-b₅ plays an important role in the catalytic reaction of LmCYP6FD1 toward 7-EC in our in vitro experiments. Further study is needed to clarify the role of LmCyt-b₅ in CYP-mediated catalytic reactions in L. migratoria.

细胞色素b ₅（Cyt-b ₅）是一种小血红素蛋白，已知参与多种生化转化，包括细胞色素P450单加氧酶（CYP）介导的内源性和外源性化合物的代谢。Cyt-b ₅的研究更多地集中在哺乳动物中，但在昆虫中却相对较少。还没有描述来自南方蝗的Cyt-b ₅的特征和功能。我们对来自L. migratoria（LmCyt-b _5）的Cyt-b ₅的全长cDNA序列进行了测序）基于蝗虫转录组数据库的逆转录PCR（RT-PCR）。系统发育分析表明，LmCyt-b ₅与Blattodea的Cyt-b ₅密切相关。LmCyt-b ₅在卵巢，Malpighian小管，中肠，胃盲肠和脂肪体内高表达。沉默LmCyt-B ₅对的敏感性无影响L.飞蝗四个不同的杀虫剂。LmCyt-b _5的抑制或LmCyt-b ₅和LmCPR的沉默没有显着改变对底物7-乙氧基香豆素（7-EC）的总CYP活性。然而，随着LmCPR和LmCyt-B LmCYP6FD1的共表达₅一起在Sf9细胞中通过使用BAC-到北杆状病毒表达系统显著增加LmCYP6FD1的催化活性朝向7-EC与LmCYP6FD1的共表达与细胞色素P450还原酶（LmCPR相比）或LmCyt-b ₅。这些结果表明，在我们的体外实验中，LmCyt-b ₅在LmCYP6FD1向7-EC的催化反应中起重要作用。需要进一步的研究以阐明LmCyt-b ₅在偏头痛L. CYP介导的催化反应中的作用。