TABLE 1.

Phosphorylation of PSD scaffold elements under different activity states of CaMKII.

Protein Accession number	Phosphorylated Peptide	Residue	Relative phosphorylation
			1	2	3	4
Densin-180 UniProtKB: P70587	R.IVGVPLELEQ[ST]*HR.H	S-831 or T-832	0.02 0.22	1.00 1.00	0.47 0.66	0.35 0.08
SAPAP1 UniProtKB: P97836	K.ATQPS*LTELTTLK.I	S-389	0.60	1.00	1.14	0.44
SAPAP1 UniProtKB: P97836	K.FQS*VGVQVEEEK.C	S-696	0.11	1.00	0.62	0.24
SAPAP1 UniProtKB: P97836	R.ERS*LESSQR.Q	S-947	0.62	1.00	0.88	0.33
SAPAP2 UniProtKB: P97837	R.EKS*LDLPDR.Q	S-1012	0.81	1.00	0.96	0.26
SAPAP3 UniProtKB: P97838	K.ERS*LDSVDR.Q	S-930	0.51	1.00	0.95	0.37
Shank1 UniProtKB:Q9WV48	K.RLPPPAIS*LR.S	S-783	0.41 0.36	1.00 1.00	0.86 0.81	0.29 0.14
Shank3 UniProtKB: Q9JLU4	R.SKS*MTAELEELASIR.R	S-769	0.20 0.39	1.00 1.00	0.63 0.72	0.09 0.12
Shank3 UniProtKB: Q9JLU4	R.S*LGEEPVGGLGSLLDPAK.K	S-1586	0.68 0.34	1.00 1.00	1.13 0.90	0.65 0.11
Spinophilin (PP1) UniProtKB: O35274	R.A[SS]*LNENVDHSALLK.L	S-99 or S-100	0.30 0.49	1.00 1.00	0.74 1.05	0.38 0.42

PSD samples were phosphorylated under four different conditions as follows:

1: 5min on ice in Ca²⁺; 2: 5min on ice in Ca²⁺,10 min at 37°C in Ca²⁺; 3: 5 min on ice in Ca²⁺, 10 min at 37°C in EGTA; 4: 5 min on ice in EGTA, 10 min at 37°C in EGTA. Relative abundances of phophopeptides under each phosphorylation condition (1–4) were evaluated in two experiments. Both values are listed when available. Phosphorylated residues are depicted by an asterisk (*). Sequences carrying homologous phosphorylation sites on the C-terminals of SAPAPs are underlined. Comparison of columns 2 and 3 indicate differences in the efficiencies of phosphorylation of a particular residue by the calmodulin-bound form of CaMKII in the presence of Ca²⁺ (2) and by the autonomous form of CaMKII in the absence of Ca²⁺ (3).