Adunyah S E, Dean W L
Cell Calcium. 1986 Jun;7(3):193-202. doi: 10.1016/0143-4160(86)90023-0.
The effects of phorbol esters and diacylglycerols on Ca2+ transport in isolated human platelet membranes were determined. Phorbol 12-myristate 13-acetate (PMA) stimulated Ca2+-ATPase activity in crude and purified internal platelet membranes approximately 2-fold with half-maximal stimulation occurring at 10 nM. Dilauroylglycerol also stimulated Ca2+-ATPase activity half-maximally at a concentration of 7.5 microM, but dioctanoylglycerol was without effect at up to 30 microM. PMA also inhibited Ca2+ uptake when added before or after commencement of ATP-dependent transport. PMA (25 nM) doubled the rate of Ca2+ efflux from passively loaded membranes in the absence of ATP. No protein kinase C activity was detected in crude or purified membranes by histone phosphorylation or endogenous protein phosphorylation assays. These results suggest that PMA and dilauroylglycerol stimulate Ca2+-ATPase activity and inhibit ATP-dependent Ca2+ transport by increasing the permeability of the membranes to Ca2+.
测定了佛波酯和二酰基甘油对分离的人血小板膜中钙离子转运的影响。佛波醇12 -肉豆蔻酸酯13 -乙酸酯（PMA）刺激粗制和纯化的血小板内膜中的钙离子ATP酶活性约2倍，半最大刺激浓度出现在10 nM。二月桂酰甘油在浓度为7.5 μM时也能半最大程度地刺激钙离子ATP酶活性，但二辛酰甘油在高达30 μM时无作用。在ATP依赖性转运开始之前或之后添加PMA时，也会抑制钙离子摄取。在无ATP的情况下，PMA（25 nM）使被动加载膜中的钙离子外流速率加倍。通过组蛋白磷酸化或内源性蛋白质磷酸化测定，在粗制或纯化的膜中均未检测到蛋白激酶C活性。这些结果表明，PMA和二月桂酰甘油通过增加膜对钙离子的通透性来刺激钙离子ATP酶活性并抑制ATP依赖性钙离子转运。
