Protein Tyrosine Phosphatase Receptor Type R (PTPRR) Reduces AChR Clustering by Dephosphorylating MuSK

Figure 4

PTPRR dephosphorylated MuSK-Tyr754. (a) HEK293T cells were transiently transfected with Flag-MuSK or empty vector plasmids. Proteins were separated by SDS-PAGE and stained with Coomassie Blue. Bands corresponding to MuSK were excised, digested with trypsin, and analyzed by LC-MS. The LC peaks corresponding to the peptide fragments containing Tyr-553, Tyr-750, Tyr-754, and Tyr-755 in MuSK fractions were further analyzed by MS/MS. (b) HEK293T cells were transiently transfected with PTPRR, MuSK, or MuSK Y553/750/754F. MuSK was isolated by immunoprecipitation with anti-Flag antibody, probed with PY754 antibody to reveal pY-MuSK Y754, and probed with 4G10 to reveal total pY-MuSK. Lysates were probed with antibodies against MuSK, pY-MuSK, and β-actin. (c) HEK293T cells were transiently transfected with PTPRR, MuSK, MuSK Y553F, MuSK Y750F, MuSK Y754F, or MuSK Y755F. MuSK was isolated by immunoprecipitation with anti-Flag antibody and probed with 4G10 to reveal pY-MuSK. Lysates were probed with antibodies against MuSK, PTPRR, pY-MuSK, and β-actin. The data were obtained from at least three experiments. Data were shown as . NS: no significant difference. and .

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