标题：Stimulation of Ca2+-dependent neurotransmitter release and presynaptic nerve terminal protein phosphorylation by calmodulin and a calmodulin-like protein isolated from synaptic vesicles
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：4
页码：1838-1842
DOI：10.1073/pnas.76.4.1838
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Synaptic vesicles have a Ca2+-dependent protein kinase system that may play a role in mediating Ca2+-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 (Ca2+-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 Ca2+ 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 Ca2+ 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.
