Figure 8.

Phosphorylation of synapsin at site 1 mostly accounts for the increase in SV recycling induced by PKA activation. Rat hippocampal neurons infected to express either ECFP–SynI or ECFP–SynI S9A under the CMV promoter were loaded with FM4-64 by exposure to 55 mm KCl for 30 s. A second epoch of FM4-64 uptake was induced by applying the same depolarizing stimulus after 20 min of recovery, followed by a 10 min incubation with forskolin (Forsk.) and bleaching of the residual fluorescence. The distribution of classes of FM4-64 fluorescence are shown (light gray, KCl; black, forskolin/KCl). p < 0.001 for neurons infected with vector before and after forskolin and for neurons expressing ECFP–SynI versus neurons expressing ECFP–SynI S9A both before and after forskolin; Bonferroni's multiple comparison test (n = 500 synapses from 3 independent experiments). Mean ± SE values of FM4-64 uptake (n = 3 independent experiments) are shown in the bottom. A.U., Arbitrary units.