Holmes R P, Yoss N L
Nature. 1983;305(5935):637-8. doi: 10.1038/305637a0.
The putative role of phosphatidic acid (PA) as a Ca2+ ionophore has offered an attractive explanation for the relationship between Ca2+ influx and the turnover of phosphoinositides in stimulated cells. The ionophoretic properties of PA are evident in its ability to translocate Ca2+ across a layer of organic solvent. When added exogenously to some cells, PA produces a physiological response and in neuroblastoma cells stimulation of Ca2+ uptake can also be detected. It was later shown that low levels of PA added exogenously to, or incorporated endogenously in liposomes, increase their permeability to Ca2+ (refs 7, 8), indicating a direct effect of PA on lipid bilayer properties. We now report, however, that we have not been able to demonstrate facilitation by PA of Ca2+ fluxes across liposomal membranes. Ascribing such a role to PA does not seem compatible with known features of biological membranes or the properties of ionophores known to translocate ions across membranes.
磷脂酸（PA）作为一种钙离子载体的假定作用，为钙离子内流与受刺激细胞中磷酸肌醇周转之间的关系提供了一个有吸引力的解释。PA的离子载体特性在其将钙离子转运穿过一层有机溶剂的能力中很明显。当外源添加到某些细胞中时，PA会产生生理反应，并且在神经母细胞瘤细胞中也能检测到对钙离子摄取的刺激。后来发现，外源添加到脂质体中或内源性掺入脂质体中的低水平PA会增加其对钙离子的通透性（参考文献7、8），这表明PA对脂质双层特性有直接影响。然而，我们现在报告，我们未能证明PA能促进钙离子穿过脂质体膜的通量。将这样的作用归因于PA似乎与生物膜的已知特征或已知能跨膜转运离子的离子载体的特性不相符。
