Figure 3.
Incorporation of α1S wild type and α1S-Y366S mutant into T-tubule/SR junctions. Double immunolabeling of transfected dysgenic myotubes with antibodies against the α1S subunit (upper row) and against the RY receptor (lower row) is shown. Colocalization of the wild-type α1S (a and b) or the α1S-Y366S mutant (c and d) with the RY receptor in clusters is indicative of a junctional location of the two channels (examples indicated with arrows). e and f, incorporation of α1S-Δ351–380 into junctions fails, even though the RY receptor forms normal clusters in these myotubes. Note that the RY clusters are also formed in myotubes not expressing α1S (asterisk). N, myotube nuclei. (Bar, 20 μm.)