Lateral mobility of presynaptic L-type calcium channels at photoreceptor ribbon synapses.
Lateral mobility of presynaptic L-type calcium channels at photoreceptor ribbon synapses.
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DOI：
10.1523/jneurosci.5921-10.2011
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发表时间：
2011-03-23
期刊：
影响因子：
--
通讯作者：
Thoreson WB
中科院分区：
文献类型：
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作者：
Mercer AJ;Chen M;Thoreson WB
在大多数突触中，突触前 Ca2+ 通道位于囊泡释放位点附近，增加此距离会降低突触强度。我们检查了虎蝾螈（Ambystoma tigrinum）视网膜感光带突触突触前 L 型 Ca2+ 通道的侧膜迁移率。通过将量子点与针对细胞外 α2δ4 Ca2+ 通道亚基的抗体偶联来跟踪单个 Ca2+ 通道的运动。 α2δ4 抗体标记光感受器末端，并与突触小泡蛋白 SV2 和 Ca2+ 通道 CaV1.4 α1 亚基的抗体共定位。结果表明，Ca2+ 通道是动态的，并且在突触带下方的有限区域内移动。该限制区域的大小由肌动蛋白和膜胆固醇调节。附近突触小泡的融合导致 Ca2+ 通道位置跳跃，将它们推向限制域的外边缘。通道迅速向中心反弹。因此，尽管 CaV 通道是可移动的，但分子支架将它们限制在带下方，即使在高释放速率下也能维持神经传递。
At most synapses, presynaptic Ca2+ channels are positioned near vesicle release sites, and increasing this distance reduces synaptic strength. We examined the lateral membrane mobility of presynaptic L-type Ca2+ channels at photoreceptor ribbon synapses of the tiger salamander (Ambystoma tigrinum) retina. Movements of individual Ca2+ channels were tracked by coupling quantum dots to an antibody against the extracellular α2δ4 Ca2+ channel subunit. α2δ4 antibodies labeled photoreceptor terminals and co-localized with antibodies to synaptic vesicle protein SV2 and Ca2+ channel CaV1.4 α1 subunits. The results show that Ca2+ channels are dynamic and move within a confined region beneath the synaptic ribbon. The size of this confinement area is regulated by actin and membrane cholesterol. Fusion of nearby synaptic vesicles caused jumps in Ca2+ channel position, propelling them towards the outer edge of the confinement domain. Channels rebounded rapidly towards the center. Thus, although CaV channels are mobile, molecular scaffolds confine them beneath the ribbon to maintain neurotransmission even at high release rates.