Figure 2.
Differential distribution of the β1a subunit and α1S subunit mutants in cotransfected dysgenic myotubes. βGFP is visualized with GFP fluorescence (upper row) and α1S subunits by immunofluorescence (lower row). a and b, wild-type α1S is colocalized with βGFP in clusters (examples indicated with arrows). c and d, the α1S-Y366S mutant is localized in clusters, but βGFP is diffusely distributed throughout the myotube. e and f, the α1S-Δ351–380 mutant is localized in a dense reticular membrane system and βGFP is diffuse. The insets show a flat region of a myotube at twice the magnification. Note the tubular nature of the membrane structure containing α1S-Δ351–380 and the clearly distinct diffuse distribution of βGFP. (Bar, 20 μm.)