Thiophosphorylation of skeletal muscle sarcoplasmic reticulum in porcine malignant hyperpyrexia.

1. The basal, Ca2+-dependent and Mg2+-dependent thiophosphorylation of malignant hyperpyrexia-susceptible (MHS) porcine skeletal muscle was investigated. 2. Seven major proteins of Mr 100,000-11,000 were substrates for thiophosphorylation. 3. Sodium molybdate significantly elevated all levels of thiophosphorylation in control sarcoplasmic reticulum, but did not effect the Ca2+-dependent thiophosphorylation of MHS samples. 4. These results suggest that MHS sarcoplasmic reticulum may have altered sensitivity to protein phosphatase inhibition.