Insertion of the full-length calcium channel α 1S subunit into triads of skeletal muscle in vitro

Abstract

A full-length and a C-terminally truncated form of the calcium channel α 1S subunit can be isolated from skeletal muscle. Here we studied whether full-length α 1S is functionally incorporated into the skeletal muscle excitation-contraction coupling apparatus. A fusion protein of α 1S with the green fluorescent protein attached to its C-terminus (α 1S-GFP) or α 1S and GFP separately (α 1S+GFP) were expressed in dysgenic myotubes, which lack endogenous α 1S. Full-length α 1S-GFP was targeted into triad junctions and restored calcium currents and excitation-contraction coupling. GFP remained colocalized with α 1S, indicating that intact α 1S-GFP was inserted into triads and that the C-terminus remained associated with the excitation-contraction coupling apparatus.