Ljungström M, Norberg L, Olaisson H, Wernstedt C, Vega F V, Arvidson G, Mårdh S
Biochim Biophys Acta. 1984 Jan 11;769(1):209-19. doi: 10.1016/0005-2736(84)90025-7.
Membrane vesicles were purified from resting corpus mucosa of pig stomachs by velocity-sedimentation on a sucrose-Ficoll step gradient. Two vesicular fractions containing the (H+ + K+)-ATPase were obtained. One fraction was tight towards KCl, the other was leaky. At 21 degrees C maximal (H+ + K+)-ATPase activities of 0.8 and 0.4 mumol X mg-1 X min-1, respectively, were observed in lyophilized vesicles. The vesicles contained a membrane-associated carbonic anhydrase, the activity of which was in 100-fold excess of the maximal ATPase activity. Both vesicular fractions were rich in phosphatidylcholine, phosphatidylethanolamine, sphingomyelin and cholesterol. The characteristics of ion permeability and transport in the tight vesicles were in agreement with corresponding data for vesicles of a tubulovesicular origin in the parietal cell. Measurement of the rate of K+ uptake into the vesicles was based on the ability of K+ to promote H+ transport. The uptake was slow and dependent on the type of anion present. The effectiveness in promoting uptake of K+ by anions was SCN- greater than NO3- greater than Cl- much greater than HCO3- greater than SO4(2-). Uptake of K+ was much more rapid at alkaline pH than at neutral or at acidic pH. Addition of CO2 at alkaline pH strongly stimulated the rate of H+ accumulation in the vesicles. The initial part of this stimulation was sensitive to acetazolamide, an inhibitor of carbonic anhydrase. A model how the (H+ + K+)-ATPase and the carbonic anhydrase may co-operate is presented. It is concluded that membrane vesicles of a tubulovesicular origin can produce acid.
通过在蔗糖 - 菲可梯度上进行速度沉降，从猪胃的静息胃体黏膜中纯化膜囊泡。获得了两个含有（H⁺ + K⁺）-ATP酶的囊泡组分。一个组分对氯化钾具有紧密性，另一个则有渗漏性。在21℃时，冻干囊泡中观察到（H⁺ + K⁺）-ATP酶的最大活性分别为0.8和0.4 μmol·mg⁻¹·min⁻¹。这些囊泡含有一种与膜相关的碳酸酐酶，其活性比最大ATP酶活性高100倍。两个囊泡组分都富含磷脂酰胆碱、磷脂酰乙醇胺、鞘磷脂和胆固醇。紧密囊泡中离子通透性和转运的特征与壁细胞中源自微管泡系统的囊泡的相应数据一致。基于K⁺促进H⁺转运的能力来测量K⁺进入囊泡的速率。摄取缓慢且依赖于存在的阴离子类型。阴离子促进K⁺摄取的有效性为SCN⁻＞NO₃⁻＞Cl⁻＞＞HCO₃⁻＞SO₄²⁻。在碱性pH下K⁺的摄取比在中性或酸性pH下快得多。在碱性pH下添加CO₂强烈刺激囊泡中H⁺积累的速率。这种刺激的初始部分对碳酸酐酶抑制剂乙酰唑胺敏感。提出了一个关于（H⁺ + K⁺）-ATP酶和碳酸酐酶如何协同作用的模型。得出的结论是，源自微管泡系统的膜囊泡可以产生酸。
