Fig. 6.

Fig. 6.

Hydrophobic residues (L₄₉₆L₅₀₀W₅₀₃) in the β_1a distal C terminus are not important for skeletal muscle EC coupling. (A) Amino acid sequence of rabbit β_1a C terminus depicting the position of the three hydrophobic residues LLW (red box with yellow filling), which were exchanged with alanines (AAA). (B) Relaxed myotubes expressing triple mutant β_1a(LLW-AAA) (n = 16) displayed Q_max values similar (P > 0.05) to β_1a (n = 16). (Right) Exemplar charge movement recording from relaxed myotubes expressing β_1a(LLW-AAA). (Scale bars, 5 ms [horizontal], 3 pA/pF [vertical].) (C) Plots of voltage dependence of maximal Ca²⁺ transients were indistinguishable (P > 0.05) between β_1a(LLW-AAA) (n = 13) and β_1a (n = 9)-expressing relaxed myotubes. (Right) Exemplar Ca²⁺ transient recordings from relaxed myotubes expressing mutant β_1a(LLW-AAA). (Scale bars, 50 ms [horizontal], ΔF/F₀ = 1 [vertical].) Error bars indicate SEM. P determined by unpaired Student’s t test.