Figure 3
MuSK autoantibodies specifically bind MuSK.
(A) Detection of secreted MuSK-AP from COS-7 cells by Western blot analysis with MuSK autoantibodies. The culture supernatants from COS-7 cells transfected with MuSK-AP (lane 1) or vector alone (lane 2) were immunoblotted with the MuSK antibodies, and the same immmunoblots were reprobed with an anti–alkaline phosphatase (anti-AP) antibody. (B) Specific binding of MuSK autoantibodies to MuSK in C2C12 myotubes. Myotubes were treated with agrin (1 nM for 18 h) and double labeled, first with rhodamine-conjugated BTX (left), and then with MuSK antibodies followed by fluorescein-conjugated secondary antibodies (middle). AChRs and MuSK colocalized, as shown by the overlay of red and green fluorescence (right). Green blotches are artifact. Scale bar: 20 μm.
