Hormone-responsive alkaline proteinase in rat skeletal muscle is not a mast cell-derived enzyme

M. Mayer, M. Chaouat, O. Z. Lernau, E. Shafrir

Research output: Contribution to journalArticlepeer-review


Proteinase activity was determined in myofibrils from intact rat skeletal muscle and from skeletal muscle myocytes grown in culture. In vivo administration of the mast cell degranulator compound 48 80 abolished the alkaline proteinase activity in myofibrils obtained from normal or streptozotocin-diabetic rats. Exposure of myocytes to compound 48 80 in cell cultures had no effect on their myofibrillar proteinase activity, nor did it affect the rate of overall protein degradation in these cells. Co-incubation of cultured mast cells (line P815Y) with myocytes followed by sonication of the cell mixture resulted in a marked reduction of the proteinase activity in the pellet fraction, suggesting that the mast cells contain inhibitor(s) of myofibrillar proteinase activity. It is suggested that the myofibril-bound alkaline proteinase activity is not a mast cell-derived enzyme but a genuine component of muscle cells. The in vivo 48 80-induced reduction of muscle myofibrillar proteinase activity appears to be due to release of a soluble inhibitory activity rather than removal of mast cell proteinase from the tissue by degranulation.

Original languageEnglish
Pages (from-to)292-297
Number of pages6
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Issue number2
StatePublished - 30 May 1985
Externally publishedYes


  • (Rat skeletal muscle)
  • Alkaline proteinase
  • Enzyme origin

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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