Best-Belpomme M, Courgeon A M, Rambach A
Proc Natl Acad Sci U S A. 1978 Dec;75(12):6102-6. doi: 10.1073/pnas.75.12.6102.
Drosophila melanogaster cell lines Kc and Ca and clones FC and RF6, cultured in vitro, have no detectable beta-galactosidase (beta-galactoside galactohydrolase, EC 3.2.1.23) activity (as measured by hydrolysis of o-nitrophenyl-beta-D-galoctoside). Ecdysterone, a hormonal steroid of critical importance in insect physiology, clearly induces beta-galactosidase activity in D. melanogaster cells cultured in vitro. Induction occurs in cell lines or clones known to be sensitive to ecdysterone (K, Ca, and Fc) and does not occur in clones known to be resistant to the hormone (RF6). Some properties of the hormone-induced beta-galactosidase activity were studied. The Km for o-nitrophenyl galactoside is 0.35 mM and the Ki for lactose is 12 mM (similar to those of Escherichia coli beta-galactosidase); the activity can be recovered after sodium dodecyl sulfate treatment; the enzyme is a tetramer (Mr of the monomer is 64,000).
在体外培养的果蝇细胞系Kc和Ca以及克隆FC和RF6，没有可检测到的β-半乳糖苷酶（β-半乳糖苷半乳糖水解酶，EC 3.2.1.23）活性（通过邻硝基苯基-β-D-半乳糖苷的水解来测量）。蜕皮甾酮是昆虫生理学中至关重要的一种激素类固醇，它能明显诱导体外培养的果蝇细胞中的β-半乳糖苷酶活性。诱导作用发生在已知对蜕皮甾酮敏感的细胞系或克隆（K、Ca和Fc）中，而在已知对该激素有抗性的克隆（RF6）中则不发生。对激素诱导的β-半乳糖苷酶活性的一些特性进行了研究。邻硝基苯基半乳糖苷的Km为0.35 mM，乳糖的Ki为12 mM（与大肠杆菌β-半乳糖苷酶的相似）；该活性在十二烷基硫酸钠处理后仍可恢复；该酶是一种四聚体（单体的Mr为64,000）。
