DeLorenzo R J, Freedman S D, Yohe W B, Maurer S C
Proc Natl Acad Sci U S A. 1979 Apr;76(4):1838-42. doi: 10.1073/pnas.76.4.1838.
Synaptic vesicles have a Ca(2+)-dependent protein kinase system that may play a role in mediating Ca(2+)-stimulated neurotransmitter release and vesicle function. Calcium's ability to initiate norepinephrine release and protein phosphorylation in synaptic vesicle preparations was shown to be stimulated by the presence of an endogenous heat-stable vesicle protein fraction. The heat stability and characteristics of this endogenous vesicle fraction were similar to those of calmodulin (Ca(2+)-dependent regular protein) isolated from rat and bovine brain. Calmodulin, like endogenous heat-stable vesicle factor, restored calcium's ability to stimulate vesicle neurotransmitter release and protein kinase activity. Calmodulin-like vesicle protein and purified calmodulin were also equally effective in stimulating cyclic nucleotide-dependent phosphodiesterase, further indicating that these two proteins are functionally equivalent. Depolarization-dependent Ca(2+) uptake in intact synaptosomes simultaneously stimulated release of neurotransmitter and phosphorylation of particular synaptic vesicle proteins that were shown in the isolated vesicle preparation to be dependent on Ca(2+) and calmodulin. The results suggest that calcium's effects on neurotransmitter release and presynaptic nerve terminal protein phosphorylation may be mediated by endogenous calmodulin-like proteins.
突触小泡具有一种依赖钙离子的蛋白激酶系统，该系统可能在介导钙离子刺激的神经递质释放和小泡功能中发挥作用。研究表明，在内源性热稳定小泡蛋白组分存在的情况下，钙离子在突触小泡制剂中引发去甲肾上腺素释放和蛋白磷酸化的能力会受到刺激。这种内源性小泡组分的热稳定性和特性与从大鼠和牛脑中分离出的钙调蛋白（依赖钙离子的调节蛋白）相似。与内源性热稳定小泡因子一样，钙调蛋白恢复了钙离子刺激小泡神经递质释放和蛋白激酶活性的能力。类钙调蛋白小泡蛋白和纯化的钙调蛋白在刺激环核苷酸依赖性磷酸二酯酶方面同样有效，这进一步表明这两种蛋白在功能上是等效的。完整突触体中依赖去极化的钙离子摄取同时刺激了神经递质的释放以及特定突触小泡蛋白的磷酸化，在分离的小泡制剂中显示这些蛋白依赖于钙离子和钙调蛋白。结果表明，钙离子对神经递质释放和突触前神经末梢蛋白磷酸化的影响可能由内源性类钙调蛋白介导。
