Holzinger F, Frick C, Wink M
Institut für Pharmazeutische Biologie, Universität Heidelberg, Germany.
FEBS Lett. 1992 Dec 21;314(3):477-80. doi: 10.1016/0014-5793(92)81530-y.
The Monarch (Danaus plexippus) sequesters cardiac glycosides for its chemical defence against predators. Larvae and adults of this butterfly are insensitive towards dietary cardiac glycosides, whereas other Lepidoptera, such as Manduca sexta and Creatonotos transiens are sensitive and intoxicated by ouabain. Ouabain inhibits the Na+,K(+)-ATPase by binding to its alpha-subunit. We have amplified and cloned the DNA sequence encoding the respective ouabain binding site. Instead of the amino acid asparagine at position 122 in ouabain-sensitive insects, the Monarch has a histidine in the putative ouabain binding site, which consists of about 12 amino acids. This change may explain the ouabain insensitivity.
黑脉金斑蝶（帝王蝶）会摄取强心苷用于抵御捕食者的化学防御。这种蝴蝶的幼虫和成虫对饮食中的强心苷不敏感，而其他鳞翅目昆虫，如烟草天蛾和桃斑蛾对哇巴因敏感并会被其毒害。哇巴因通过与钠钾ATP酶的α亚基结合来抑制该酶。我们已经扩增并克隆了编码相应哇巴因结合位点的DNA序列。在对哇巴因敏感的昆虫中，假定的哇巴因结合位点第122位氨基酸是天冬酰胺，而黑脉金斑蝶在此位置是组氨酸，该结合位点约由12个氨基酸组成。这一变化可能解释了其对哇巴因的不敏感性。
