Fig. 1.

Synaptic protein expression during neuronal development. Western blot analysis of cell extracts from neuronal cultures maintained in vitro for 2, 7, and 15 d (DIV) and from rat brain at different developmental stages (E18, P1, and adult). SV (synaptophysin, synaptotagmin, synaptobrevin/VAMP2, and rab3a) and plasma membrane (SNAP-25 and syntaxin) proteins are expressed since early developmental stages and undergo a progressive increase in their expression in parallel with neuronal maturation. The same amount of material (30 μg) has been loaded in each lane.