Functional studies for presynatic proteins which may control efficiency of synaptic transmission

神经递质的释放是通过动作电位激活的电压依赖性钙通道进入突触前神经末梢而触发的。最近，在突触前终末发现了各种蛋白质。例如，形成核心复合体并参与突触小泡吐出的SNARE蛋白、突触小泡蛋白或与钙离子感受器相关的突触小泡、也形成复合体的活动区细胞基质蛋白和可能动员突触小泡的运动蛋白，以及可能控制钙通道活动的通道相互作用蛋白。为了研究这些蛋白在调节突触传递效率中的可能作用，我们采用了长期培养的大鼠颈上神经节神经元之间形成的突触。我们引入突触前蛋白的外源合成肽、蛋白质或转基因的cDNA，并通过记录突触前动作电位产生的兴奋性突触后电位来监测突触传递的变化。我们揭示了一种调控SNARE复合体形成的机制，即通过结合钙调素与合成素的结合，脑中表达的三种钙通道的功能差异，活跃区细胞基质蛋白的可能作用，通过Sv2与钙结合调节细胞外排出，4)&gt；4)&gt；结合N-钙类型的G蛋白βγ亚基调节细胞吐出。通道^&lt；5)&gt；，肌球蛋白IIB对突触小泡运输的调节，而不是IIA、Va或Vb(准备重新提交)。

Neurotransmitter release is triggered by Ca^<2+> entered into presynaptic nerve terminals through voltage-dependent Ca^<2+> channels activated by an action potential. Recently, various proteins were found in presynaptic terminals. For example, SNARE proteins which form a core complex and involved in synaptic vesicle exocytosis, synaptic vesicle proteins or synaptic vesicle associated with Ca^<2+>sensor proteins, active zone cytomatrix proteins that also form a complex and motor proteins that may mobilize synaptic vesicles, and Ca^<2+> channel interacting proteins which may control Ca^<2+> channel activity.To examine possible roles of these proteins in regulation of synaptic transmission efficiency, we employed synapses formed between rat superior cervical ganglion neurons in long-term culture. We introduced exogenous synthesized peptides or, protein, or transfected cDNAs of a presynaptic protein and monitored changes in synaptic transmissionby recording excitatory postsynaptic potentials generated by presynaptic action potentials. We revealed a mechanism of regulation of SNARE complex formation by binding of Ca^<2+>/Calmodulin to syntaxin IA^<1)>, functional differences between three types of Ca^<2+> channels expressed in the brain^<2)> a possible role of cytomatrix proteins at the active zone^<3)>, regulation of exocytosis by SV2 binding to a Ca^<2+> sensor synaptotagmin^<4)>, regulation of exocytosis by G-protein βγ subunit binding to N-type Ca^<2+> channel^<5)>, regulation of synaptic vesicle trafficking by myosin IIB but not by IIA, Va or Vb (preparing for re-submission).