Dowd F, Watson E L, Lau Y S, Justin J, Pasieniuk J, Jacobson K L
J Dent Res. 1987 Feb;66(2):557-63. doi: 10.1177/00220345870660022901.
Rat parotid secretory granule membranes were examined for the presence of calcium-dependent protein kinase activities and kinase substrates. Protein kinase C (C-kinase), which is stimulated by certain phospholipids, was present in the membranes, as indicated by its ability to catalyze the phosphorylation of histone. Two substrates for protein kinase C were seen in the granule membranes. The cytosolic fraction from the cell contained kinase activity, which was stimulated by phosphatidylserine and which caused the phosphorylation of two granule membrane polypeptides. In addition, when both granule membranes and cytosol were incubated together, phosphorylation of the cytosolic substrates was inhibited, indicating that the granule membrane substrates were phosphorylated preferentially. The results indicate that the granule membranes may react with cytosolic protein kinase C activity in a way which would direct an intracellular calcium and diacylglycerol signal toward the granule membrane. Since these signals occur during stimulation by various agonists, the mechanism may contribute to secretion.
对大鼠腮腺分泌颗粒膜进行检测，以确定是否存在钙依赖性蛋白激酶活性和激酶底物。受某些磷脂刺激的蛋白激酶C（C激酶）存在于膜中，这可通过其催化组蛋白磷酸化的能力来表明。在颗粒膜中发现了两种蛋白激酶C的底物。细胞的胞质部分含有激酶活性，该活性受磷脂酰丝氨酸刺激，并导致两种颗粒膜多肽的磷酸化。此外，当颗粒膜和胞质溶胶一起孵育时，胞质底物的磷酸化受到抑制，这表明颗粒膜底物被优先磷酸化。结果表明，颗粒膜可能以一种将细胞内钙和二酰基甘油信号导向颗粒膜的方式与胞质蛋白激酶C活性发生反应。由于这些信号在各种激动剂刺激期间出现，该机制可能有助于分泌。
