Journal of Muscle Research & Cell Motility

, Volume 11, Issue 3, pp 271–279

Digestion of proteins associated with the Z-disc by calpain

  • Belinda Bullard
  • Gillian Sainsbury
  • Nigel Miller
Papers

DOI: 10.1007/BF01843580

Cite this article as:
Bullard, B., Sainsbury, G. & Miller, N. J Muscle Res Cell Motil (1990) 11: 271. doi:10.1007/BF01843580

Summary

The Z-disc of striated muscle is degraded by the Ca2+ -activated proteinase, calpain, during autolysis of muscle fibres. The effect of calpain on proteins in preparations of Z-discs isolated fromLethocerus flight muscle has been studied. Calpain releasesα-actinin from the Z-disc and digests two hydrophobic proteins associated with the Z-disc, zeelin 1 (35 kD) and zeelin 2 (23 kD). The Ca2+ sensitivity of zeelin digestion is shifted to lower Ca2+ concentrations (within the physiological range) in the presence of the phospholipids phosphatidyl inositol or phosphatidyl choline and diacylglycerol. The release ofα-actinin is not affected by phospholipid. Preparations of isolated Z-discs have five times as much associated phospholipid (w/w) as myofibrils and the composition of the lipid differs from that of myofibrils. In muscle fibres the action of calpain on zeelins may be controlled by the composition of phospholipid in the fibres as well as by Ca2+.

Copyright information

© Chapman and Hall Ltd 1990

Authors and Affiliations

  • Belinda Bullard
    • 1
  • Gillian Sainsbury
    • 1
  • Nigel Miller
    • 1
  1. 1.AFRC Institute of Animal Physiology and Genetics ResearchBabrahamUK
  2. 2.European Molecular Biology LaboratoryHeidelbergWest Germany
  3. 3.Department of PharmacologyOxfordUK

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