Gastric H+ secretion: histamine (cAMP-mediated) activation of protein phosphorylation.
Gastric H+ secretion: histamine (cAMP-mediated) activation of protein phosphorylation.
复制标题
胃 H 分泌：组胺（cAMP 介导）激活蛋白质磷酸化。
DOI：
10.1016/0167-4889(88)90106-1
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Cuppoletti,J
中科院分区：
文献类型：
--
作者：
Malinowska,DH;Sachs,G;Cuppoletti,J
胃壁细胞H+分泌的激活涉及分泌膜形态、代谢活性和离子通路的重大变化。这些变化是由组胺与h2受体结合引起的，升高cAMP水平，并可能激活cAMP依赖性蛋白激酶。同时，胞内游离Ca2+浓度[Ca2+]i增加。研究确定了camp介导的蛋白磷酸化是否伴随着H+分泌的组胺激活，并对壁细胞中作为camp依赖性蛋白激酶底物的主要蛋白种类进行了分类。采用Nycodenz膨体密度离心法制备的80%纯兔壁细胞。为了仅研究camp介导的效应，通过消耗细胞内Ca2+储存并在Ca2+无条件下进行实验，消除了这些细胞中[Ca2+]ii的组胺依赖性变化。然后在未刺激（西咪替丁处理）和组胺刺激的细胞中测量酸分泌和蛋白质磷酸化的稳态水平。在完整的壁细胞中，伴随着组胺刺激H+分泌，观察到蛋白磷酸化水平的增加。在上清中发现的显著变化的磷酸化蛋白显示亚基大小约为。148、130、47和43 kDa，在微粒体分数中包括大约。130 51和47 kDa。在壁细胞匀浆中，使用[γ-32P]ATP， cAMP诱导了8种上清蛋白和12种微粒体蛋白的显著磷酸化，其中包括完整壁细胞中发现的组胺依赖性磷酸化蛋白，除了51 kDa微粒体蛋白。作为一种可行的假设，这些蛋白质参与了壁细胞的刺激-分泌偶联。
Activation of H+secretion by the gastric parietal cell involves major changes in morphology, metabolic activity and ion pathways of the secretory membrane. These changes are elicited by histamine binding to the H2receptor, raising cAMP levels and presumably activating cAMP-dependent protein kinase. Concomitantly, the intracellular free Ca2+concentration, [Ca2+]i, increases. Studies were performed to determine whether cAMP-mediated protein phosphorylation accompanies histamine activation of H+secretion and to catalogue the major protein species serving as substrates for cAMP—dependent protein kinase in the parietal cell. 80% pure rabbit parietal cells, prepared by Nycodenz bouyant density centrifugation, were used. To investigate only cAMP-mediated effects, histamine-dependent changes in [Ca2+]iin these cells were abolished by depleting intracellular Ca2+stores and performing experiments under Ca2+-free conditions. Acid secretion and steady-state levels of protein phosphorylation were then measured in unstimulated (cimetidine-treated) and histamine-stimulated cells. In intact parietal cells, concommitant with histamine stimulation of H+secretion, increases in the level of protein phosphorylation were observed. Significantly changing phosphoproteins found in supernatant fractions showed apparent subunit sizes of approx. 148, 130, 47 and 43 kDa, and in microsomal fractions included those at approx. 130, 51 and 47 kDa. In parietal cell homogenates, using [γ-32P]ATP, cAMP elicited significant phosphorylation of eight supernatant proteins and twelve microsomal proteins, which included the histamine-dependent phosphoproteins found in the intact parietal cell, except for the 51 kDa microsomal protein. As a working hypothesis, these proteins are involved in stimulus-secretion coupling in the parietal cell.