Caruso-Neves C, Meyer-Fernandes J R, Saad-Nehme J, Proverbio F, Marín R, Lopes A G
Instituto de Biofísica Carlos Chagas Filho, UFRJ, Rio de Janeiro, Brazil.
Comp Biochem Physiol B Biochem Mol Biol. 1998 Apr;119(4):807-11. doi: 10.1016/s0305-0491(98)00057-1.
In the present paper, we show the existence of a furosemide-sensitive Na(+)-stimulated, Mg(2+)-dependent ATPase activity in cell lysates of Malpighian tubular cells from Rhodnius prolixus, which could be the biochemical expression of the Na(+)-pump. The main characteristics of this activity are: (1) K0.5 for Na+ = 1.49 +/- 0.18 mM, (2) Vmax = 2.8 +/- 0.1 nmol inorganic orthophosphate (Pi).mg prot-1.min-1, (3) it is fully abolished by 2 mM furosemide, (4)it is insensitive to ouabain concentrations up to 10(-2) M, (5) it is sensitive to the presence of vanadate in the incubation medium indicating it to be a P-type ATPase, and (6) it is stimulated by nanomolar concentrations of Ca2+ in the incubation medium.
在本论文中，我们证明了在致倦库蚊马氏管细胞裂解物中存在一种速尿敏感的、钠刺激的、镁依赖的ATP酶活性，这可能是钠泵的生化表现。该活性的主要特征如下：（1）钠的半最大效应浓度（K0.5）= 1.49±0.18 mM，（2）最大反应速度（Vmax）= 2.8±0.1 nmol无机正磷酸盐（Pi）·mg蛋白-1·min-1，（3）2 mM速尿可使其完全丧失活性，（4）对高达10^(-2) M的哇巴因浓度不敏感，（5）对孵育介质中钒酸盐的存在敏感，表明它是一种P型ATP酶，（6）孵育介质中纳摩尔浓度的钙离子可刺激该活性。
