Figure 7.

Activity-dependent phosphorylation of Tomo1 participates in synaptic scaling. A, IP of endogenous Tomo1 from cultured hippocampal neurons (bottom; Western) following in situ ³²P labeling indicates that Tomo1 is phosphorylated (top; ³²P radiolabel detection). The level of phosphorylation was affected by alterations in neural activity (± picrotoxin, 50 μm. 4.5 h) and Cdk5 activity (± Rosco, 100 μm, 4.5 h). B, Averaged extent of in situ Tomo1 phosphorylation relative to vehicle-treated control (0.5% DMSO, n = 3 cell preparations). Extent of phosphorylation was quantified from density of ³²P-band corresponding to Tomo1 immunoreactivity. C, Averaged changes in presynaptic vGpH fluorescence to 100 pulse stimulus (10 Hz) following chronic silencing of neuronal activity (CNQX, 40 μm, 24 h) relative to control (vehicle only) in sh-Tomo1-transfected and control (empty vector) conditions. D, Averaged Δf − f₀ for all boutons of specified conditions (n, con = 121, con + CNQX = 134, sh-Tomo1 = 750, sh-Tomo1 + CNQX = 409). *p < 0.05.