Fig 6.

Dok7 expression increases MuSK phosphorylation and its colocalization with phosphotyrosine. (A) MuSK activation by Dok7 was demonstrated by co-expression of SBP-MuSK and HA-tagged Dok7 in COS-7 cells. Surface MuSK was labelled with Cy3-conjugated streptavidin (red) at 4 °C followed by incubation at 37 °C. After cell fixation, the cells were stained with an antibody against phosphotyrosine (pTyr, blue) and an antibody against the HA-tag of Dok7 (green). Scale bar = 25 μm. (B) Quantification of MuSK/pTyr colocalization using a threshold-and object-based colocalization analysis (as described in the Materials and methods) is shown. Error bars indicate the SEM (n ≥ 10). (C) Quantification of MuSK/Dok7 and MuSK/Dok7/pTyr colocalization during endocytosis (in min) as in (B). Error bars indicate the SEM (n ≥ 10).