Figure 2.

Restoration of synchronous release by expression of exogenous wild-type synaptotagmin I. A, Evoked EPSCs recorded from a wild-type neuron (top), an untransfected knock-out neuron (KO; middle), and a neuron transfected with wild-type synaptotagmin I (Stg I; bottom). Cells were held at -70 mV, and action potentials were induced by brief depolarizations (arrows); stimulus artifacts are blanked. B, Normalized cumulative charge released from the knock-out neurons transfected with wild-type synaptotagmin I (gray circles; n = 11). The solid line is a double exponential function fit to the data. For comparison, similar plots from wild-type (dashed) and knock-out (dotted) neurons are shown. C, Time constants of the fast, synchronous (left) and slower, asynchronous (right) components of transmitter release from knock-out neurons transfected with synaptotagmin I, as well as wild-type and knock-out neurons. D, Relative amplitudes of fast and slow components of transmitter release for the three types of neurons. Data for wild-type and knock-out neurons shown in B-D are from Nishiki and Augustine (2004).