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. 2000 Apr 18;97(9):4585–4590. doi: 10.1073/pnas.080061997

Figure 3.

Figure 3

Mapping of tyrosine phosphorylated residues in Torpedo MuSK. (A) Immunoprecipitation of activated MuSK from Torpedo electric organ. MuSK was immunoprecipitated with antibodies (2847) to MuSK, and Western blots were probed either with antibodies (2847) to MuSK or antibodies to phosphotyrosine (PY, 4G10). (B) Parent ion scans detect phosphopeptides in activated MuSK. The digest was analyzed with nanoelectrospray by using parent ion scans of m/z = 79 in the negative ion mode for the specific detection of phosphopeptides. (Top) Elution of the peptides from the desalting column with 20% methanol. (Middle) Elution with 50% methanol. (Bottom) Elution with 50% methanol, 5% ammonia. The following peptides were detected: ●, 1,216 Da (826–834) + 1P; ●●, 1,295 (826–834) + 2P; ○, 2,310 Da (826–844) + 1P; ○○, 2,390 Da (826–844) + 2P; ■, 1,235 Da (625–633) + 1P; ■*, 1,251 (625–633) + 1P (oxidized methionine); □, 3,187 Da (607–633) + 1P; □*, 3,203 Da (607–633) + 1P (oxidized methionine); ▿, 986 Da (650–656) + 1P.