Song H, Ming G, Fon E, Bellocchio E, Edwards R H, Poo M
Department of Biology, University of California at San Diego, La Jolla 92093, USA.
Neuron. 1997 May;18(5):815-26. doi: 10.1016/s0896-6273(00)80320-7.
A putative vesicular acetylcholine transporter (VAChT) was overexpressed in developing Xenopus spinal neurons by injection of rat VAChT cDNA or synthetic mRNA into Xenopus embryos. This resulted in a marked increase in the amplitude and frequency of miniature excitatory postsynaptic currents at neuromuscular synapses, reflecting an over 10-fold increase in the vesicular packaging of acetylcholine (ACh). The effect appeared in developing neurons even before synaptogenesis and was blocked by L-vesamicol, a specific blocker of ACh uptake into synaptic vesicles. Mutational studies showed that two highly conserved aspartate residues within putative transmembrane domains 4 and 10 are essential for the transport activity. These results provide direct evidence for the physiological function of a putative VAChT and demonstrate that quantal size can be regulated by changes in vesicular transporter activity.
通过将大鼠囊泡乙酰胆碱转运体（VAChT）cDNA或合成mRNA注射到非洲爪蟾胚胎中，一种假定的VAChT在发育中的非洲爪蟾脊髓神经元中过表达。这导致神经肌肉突触处微小兴奋性突触后电流的幅度和频率显著增加，反映出乙酰胆碱（ACh）的囊泡包装增加了10倍以上。这种效应甚至在突触形成之前就在发育中的神经元中出现，并被L-vesamicol（一种将ACh摄取到突触小泡中的特异性阻滞剂）所阻断。突变研究表明，假定的跨膜结构域4和10内的两个高度保守的天冬氨酸残基对于转运活性至关重要。这些结果为假定的VAChT的生理功能提供了直接证据，并证明量子大小可以通过囊泡转运体活性的变化来调节。
