Olaisson H, Arvidson G, Ma J Y, Mårdh S
Department of Medical and Physiological Chemistry, University of Uppsala, Sweden.
Acta Physiol Scand. 1990 Nov;140(3):383-92. doi: 10.1111/j.1748-1716.1990.tb09013.x.
A membrane fraction containing H,K-ATPase (EC 3.6.1.36) was prepared from pig gastric mucosa and found to contain phospholipase A2 (EC 3.1.1.4) and lysophospholipase (EC 3.1.1.5) activities. Washing the membranes decreased their protein content by 25%. Recovery profiles of H,K-ATPase, phospholipase A2 and lysophospholipase were similar for membranes washed either with water or with 0.15 or 1.5 M KCl. Nearly identical distribution profiles were obtained for the three enzyme activities after centrifugation of washed vesicle membranes on a linear sucrose gradient. The phospholipase A2 activity was stimulated by calcium and increased further in the presence of calmodulin. The amount of cellular radioactively labelled lysophosphatidylcholine was doubled upon cholinergic stimulation of isolated parietal cells prelabelled with [3H]glycerol or 32Pi. The liberated lyso[32P]phosphatidylcholine had its acyl chain in the sn-1 position, which implies an activation of a phospholipase A2. These findings indicate that secretagogues which increase the cytosolic Ca2+ concentration, i.e. acetylcholine, histamine and gastrin, may activate a phospholipase A2 in the parietal cell.
从猪胃黏膜制备了含有H，K - ATP酶（EC 3.6.1.36）的膜组分，发现其含有磷脂酶A2（EC 3.1.1.4）和溶血磷脂酶（EC 3.1.1.5）活性。洗涤这些膜使其蛋白质含量降低了25%。用水或0.15或1.5 M KCl洗涤的膜，H，K - ATP酶、磷脂酶A2和溶血磷脂酶的回收曲线相似。用线性蔗糖梯度离心洗涤后的囊泡膜后，三种酶活性获得了几乎相同的分布曲线。磷脂酶A2活性受钙刺激，在钙调蛋白存在时进一步增加。用[3H]甘油或32Pi预标记的分离壁细胞经胆碱能刺激后，细胞内放射性标记的溶血磷脂酰胆碱量增加了一倍。释放的溶血[32P]磷脂酰胆碱的酰基链位于sn - 1位，这意味着磷脂酶A2被激活。这些发现表明，增加胞质Ca2+浓度的促分泌剂，即乙酰胆碱、组胺和胃泌素，可能激活壁细胞中的磷脂酶A2。
