Suematsu E, Hirata M, Kuriyama H
Biochim Biophys Acta. 1984 Jun 13;773(1):83-90. doi: 10.1016/0005-2736(84)90552-2.
Sarcolemmal fractions of vascular smooth muscles were prepared from porcine thoracic aortae by differential and sucrose density gradient centrifugation. In these fractions, there was a high activity of 5'-nucleotidase, a putative marker enzyme of plasma membrane, and a low activity of rotenone insensitive NADH-cytochrome c reductase a marker of sarcoplasmic reticulum. In these fractions, the Ca2+ uptake was ATP-dependent. A low concentration of saponin which inhibited Ca2+ uptake by the plasma membrane but not by the sarcoplasmic reticulum, inhibited 65% of the Ca2+ uptake of this fraction. The Ca2+ uptake of this fraction was enhanced by cAMP- and cGMP-dependent protein kinases, and by calmodulin. The cAMP-dependent protein kinase enhanced the phosphorylation of 28 and 22 kDa proteins, while the cGMP-dependent protein kinase phosphorylated the 35 kDa protein. The phosphorylation of 100, 75, 65, 41 and 22 kDa proteins was enhanced by Ca2+ and calmodulin. These results indicate that cAMP- and cGMP-dependent protein kinases as well as calmodulin play important roles in Ca2+ transport in the sarcolemma, and that the phosphorylated proteins may be associated with an enhancement of Ca2+ transport in the sarcolemma.
采用差速离心和蔗糖密度梯度离心法从猪胸主动脉制备血管平滑肌肌膜组分。在这些组分中，存在高活性的5'-核苷酸酶（一种假定的质膜标志酶）和低活性的鱼藤酮不敏感的NADH-细胞色素c还原酶（一种肌浆网标志酶）。在这些组分中，Ca2+摄取是ATP依赖性的。低浓度的皂角苷可抑制质膜对Ca2+的摄取，但不抑制肌浆网对Ca2+的摄取，它能抑制该组分65%的Ca2+摄取。该组分的Ca2+摄取可被cAMP和cGMP依赖性蛋白激酶以及钙调蛋白增强。cAMP依赖性蛋白激酶增强了28 kDa和22 kDa蛋白质的磷酸化，而cGMP依赖性蛋白激酶使35 kDa蛋白质磷酸化。Ca2+和钙调蛋白增强了100 kDa、75 kDa、65 kDa、41 kDa和22 kDa蛋白质的磷酸化。这些结果表明，cAMP和cGMP依赖性蛋白激酶以及钙调蛋白在肌膜Ca2+转运中起重要作用，并且磷酸化的蛋白质可能与肌膜Ca2+转运的增强有关。
