Expression of recombinant GFP-JPHs or GFP-E-Syt3 in adult mouse FDB muscle fibers. Confocal images of adult mouse FDB muscle fibers expressing plasmids encoding GFP-JPH1 (A and D), GFP-JPH2 (G), or GFP-E-Syt3 (J). Fibers were counterstained with primary polyclonal antibodies against RyR (B) or monoclonal antibodies against α-actinin (E, H, and K), both revealed with Cy3-conjugated secondary antibodies. C, F, I, and L are merged images. Arrowheads indicate the surface sarcolemma. Scale bar, 2.5 μm.