Figure 1.

Synapsins do not determine the properties of basal synaptic transmission. A, A neuron expressing GFP-synapsin IIa. The area marked by a white square in the left is magnified in the right to demonstrate the synaptic localization of synapsin IIa. B, Examples of autaptic EPSCs recorded from TWT and TKO neurons as well as from TKO neurons expressing indicated synapsin isoforms. C, Mean amplitudes of evoked EPSCs in TWT (black bar, n = 46) and TKO neurons (white bar, n = 47) as well as in TKO neurons expressing indicated synapsin isoforms (gray bars). Sample sizes for each isoform are synapsin Ia (n = 34), Ib (n = 25), IIa (n = 22), IIb (n = 23), and IIIa (n = 30). D, Amplitudes of spontaneous synaptic events (mEPSCs) recorded in TWT (n = 23) and TKO neurons (n = 13) as well as in TKO neurons expressing individual synapsin isoforms: synapsin Ia (n = 27), Ib (n = 22), IIa (n = 19), IIb (n = 17), and IIIa (n = 30). EPSC and mEPSC amplitudes recorded in infected neurons were not significantly different from those recorded in uninfected TKO neurons. E, Effects of synapsin isoforms on the frequency of spontaneous synaptic events, presented as in C. Spontaneous glutamate release was twofold higher in synapsin IIb infected neurons than in TKO neurons (*p < 0.05; asterisk), whereas other synapsins had no significant effects on mEPSC frequency.