Advanced Biologicals, National Institute of Animal Health, NARO, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
Genes Cells. 2010 May;15(5):525-36. doi: 10.1111/j.1365-2443.2010.01401.x. Epub 2010 Apr 7.
Lepidoptera such as the domestic silkworm (Bombyx mori) produce proteins modified with unsialylated, mannose-rich moieties known as 'high mannose-type'N-glycans. However, we observed that, under intrinsic acetylglucosaminidase (GlcNAcase)-inhibited conditions, moth cells tend to synthesize different types of glycoform with sialic acid modification. To identify molecules essential to assemble Lepidoptera-specific N-glycans, we performed BLAST analysis on the silkworm genetic database and isolated the entire coding sequence of novel Bombyx GlcNAcase, BmGlcNAcase 2. This enzyme showed weak homology to currently known, lysosome-associated eukaryotic hexosaminidases, but it revealed remarkable similarity with recently reported glycosyl hydrolases of Spodoptera and Bombyx. Interestingly, BmGlcNAcase 2 was found to be expressed in embryos and in certain tissues of molting larvae (i.e. ovary, fat bodies, mid-intestine, skin), but not in pupae, suggesting its unique function in the carbohydrate metabolism of juvenile silkworm.
鳞翅目昆虫（如家蚕（Bombyx mori））会产生经过非唾液酸化、富含甘露糖修饰的蛋白质，这些蛋白质被称为“高甘露糖型”N-聚糖。然而，我们观察到，在内在乙酰氨基葡萄糖苷酶（GlcNAcase）抑制的条件下，蛾细胞往往会合成具有唾液酸化修饰的不同类型的糖型。为了鉴定组装鳞翅目特异性 N-聚糖所必需的分子，我们对蚕的遗传数据库进行了 BLAST 分析，并分离出新型家蚕 GlcNAcase（BmGlcNAcase 2）的完整编码序列。这种酶与目前已知的溶酶体相关的真核六糖胺酶具有微弱的同源性，但它与最近报道的鳞翅目 Spodoptera 和 Bombyx 的糖苷水解酶具有显著的相似性。有趣的是，发现 BmGlcNAcase 2 在胚胎和蜕皮幼虫的某些组织（即卵巢、脂肪体、中肠、皮肤）中表达，但不在蛹中表达，这表明它在幼虫期蚕的碳水化合物代谢中具有独特的功能。
