Research Institute of Biological Science, Katakura industries CO., LTD., 1548 Simo-okutomi, Sayama, Saitama 350-1332, Japan.
J Biosci Bioeng. 2010 Oct;110(4):386-91. doi: 10.1016/j.jbiosc.2010.04.008. Epub 2010 May 26.
In insects, β-N-acetylglucosaminidase (GlcNAcase) participates in critical physiological processes such as fertilization, metamorphosis, and glycoconjugate degradation. Insects produce glycoproteins carrying paucimannosidic-type N-glycans, the terminal GlcNAc residue of which is cleaved by a GlcNAc-linkage specific GlcNAcase, also known as the fused lobes (FDL) protein. To obtain information on the structure of GlcNAcases and insight into their contribution to physiological processes, we cloned Bombyx mori FDL (BmFDL) from silkworm larvae. The full-length cDNA (1.9 kb) encoded a protein of 633 amino acids with 42% amino acid sequence identity to Drosophila melanogaster FDL (DmFDL). Recombinant BmFDL cleaved only β-1,2-linked GlcNAc residues from the α-1,3 branch of biantennary N-glycan. This substrate specificity was similar to that of DmFDL. Microsomal FDL activity was inhibited by anti-BmFDL antibodies. Taken together, our results suggest that BmFDL is a N-glycan-processing GlcNAcase in B. mori.
在昆虫中，β-N-乙酰氨基葡萄糖苷酶（GlcNAcase）参与了受精、变态和糖缀合物降解等关键生理过程。昆虫产生带有低甘露糖型 N-聚糖的糖蛋白，其末端 GlcNAc 残基被 GlcNAc 连接特异性 GlcNAcase（也称为融合叶（FDL）蛋白）切割。为了获得有关 GlcNAcases 结构的信息并深入了解它们对生理过程的贡献，我们从家蚕幼虫中克隆了家蚕 FDL（BmFDL）。全长 cDNA（1.9 kb）编码一个 633 个氨基酸的蛋白质，与果蝇 FDL（DmFDL）的氨基酸序列有 42%的同源性。重组 BmFDL 仅从双天线 N-聚糖的α-1,3 分支上切割β-1,2 连接的 GlcNAc 残基。这种底物特异性与 DmFDL 相似。微粒体 FDL 活性被抗 BmFDL 抗体抑制。综上所述，我们的结果表明 BmFDL 是家蚕中的一种 N-聚糖加工 GlcNAcase。
