A calcium-activated protease possibly involved in myofibrillar protein turnover. Isolation of a low-calcium-requiring form of the protease

William R. Dayton, Judith V. Schollmeyer, Robert A. Lepley, Lisa R. Cortés

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169 Scopus citations

Abstract

Two forms of a calcium-activated neutral protease were isolated and purified from porcine skeletal muscle. The two forms of the protease differ markedly in their requirement for calcium with the low-calcium-requiring form showing one-half maximal activation at 45 μM calcium while the high-calcium-requiring form shows one-half maximal activation at 0.74 mM calcium. Additionally, they chromatograph differently on DEAE-cellulose, exhibit different mobilities in electrophoresis in a nondenaturing buffer, are affected differently by certain divalent cations, and have slightly different pH dependencies. Despite these differences, the purified forms of the calcium-activated protease co-chromatograph in gel permeation chromatography, have identical banding patterns on sodium dodecyl sulfate (SDS)-polyacrylamide gels, cross-react with an antibody directed against the 80 000-dalton subunit of the calcium-activated protease we originally purified from skeletal muscle (Dayton, W.R., Goll, D.E., Zeece, M.G., Robson, R.M. and Reville, W.J. (1976) Biochemistry 15, 2150-2158), and have identical effects on the ultrastructure of myofibrils. The high-calcium-requiring protease purified in this study is very likely identical to the calcium-activated protease we originally purified from skeletal muscle. The properties of the low-calcium-requiring form of the protease suggest that it is the form of the enzyme that is active in vivo.

Original languageEnglish (US)
Pages (from-to)48-61
Number of pages14
JournalBBA - Enzymology
Volume659
Issue number1
DOIs
StatePublished - May 14 1981

Bibliographical note

Funding Information:
We would hke to thank L.C. for expert technical assistance. This work was supported by grants from the Muscular Dystrophy Assocmtlon of America, the Mmnesota Leukemia Task Force and the Minnesota Agricultural Experiment Station. This IS Scientific Journal Series Paper No. J 11598, Minnesota Agrmul-tural Experiment Station, Umverslty of Minnesota, St. Paul, MN 55108, U.S.A

Keywords

  • (Myofibril)
  • Ca activation
  • Ca requirement
  • Protease
  • Protein turnover

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