(a) Using conservative cutoff criteria of q<.05, 6095 peptides (red) from 590 proteins were identified as potential MAP2 interactors. (b) Puromycin incorporation was detected via western blotting following a 1h treatment of transiently transfected HEK293 cells expressing MAP2c-WT or MAP2c-S426E in comparison to cells transfected with eGFP control for 48h. Densitometric quantification of relative puromycin incorporation normalized to MAP2 expression levels. N=4, data shown are average across experiments ± SEM. *p < 0.1, **p < 0.05. (c) Reductions in the synaptic proteome are seen in both MAP-IRLOW Sz and S1782E mice. Volcano plots showing distribution of 159 synaptically enriched proteins in NPC, MAP2-IRLOW and MAP2-IRNL Sz (N=45 pairs; N=19 MAP2-IRNL, N=26 MAP2-IRLOW). Mice with phosphomimetic mutation S1782E have synaptic proteome alterations similar to those seen in MAP2-IRLOW Sz (N=4 mice/genotype). Green dashed line indicates q-value of 0.05, red dashed line indicates q-value of 0.1.