Journal of Muscle Research & Cell Motility

, Volume 10, Issue 3, pp 197–205

Three myosin heavy chain isoforms in type 2 skeletal muscle fibres

  • Stefano Schiaffino
  • Luisa Gorza
  • Saverio Sartore
  • Leopoldo Saggin
  • Simonetta Ausoni
  • Monica Vianello
  • Kristian Gundersen
  • Terje LØmo
Article

DOI: 10.1007/BF01739810

Cite this article as:
Schiaffino, S., Gorza, L., Sartore, S. et al. J Muscle Res Cell Motil (1989) 10: 197. doi:10.1007/BF01739810

Summary

Mammalian skeletal muscles consist of three main fibre types, type 1, 2A and 2B fibres, with different myosin heavy chain (MHC) composition. We have now identified another fibre type, called type 2X fibre, characterized by a specific MHC isoform. Type 2X fibres, which are widely distributed in rat skeletal muscles, can be distinguished from 2A and 2B fibres by histochemical ATPase activity and by their unique staining pattern with seven anti-MHC monoclonal antibodies. The existence of the 2X-MHC isoform was confirmed by immunoblotting analysis using muscles containing 2X fibres as a major component, such as the normal and hyperthyroid diaphragm, and the soleus muscle after high frequency chronic stimulation. 2X-MHC contains one determinant common to 2B-MHC and another common to all type 2-MHCs, but lacks epitopes specific for 2A- and 2B-MHCs, as well as an epitope present on all other MHCs. By SDS-polyacrylamide gel electrophoresis 2X-MHC shows a lower mobility compared to 2B-MHC and appears to comigrate with 2A-MHC. Muscles containing predominantly 2X-MHC display a velocity of shortening intermediate between that of slow muscles and that of fast muscles composed predominantly of 2B fibres.

Copyright information

© Chapman and Hall Ltd. 1989

Authors and Affiliations

  • Stefano Schiaffino
    • 1
    • 2
  • Luisa Gorza
    • 1
    • 2
  • Saverio Sartore
    • 1
  • Leopoldo Saggin
    • 1
    • 2
  • Simonetta Ausoni
    • 1
    • 2
  • Monica Vianello
    • 1
  • Kristian Gundersen
    • 3
  • Terje LØmo
    • 3
  1. 1.Institute of General PathologyUniversity of PadovaPadovaItaly
  2. 2.CNR Unit for Muscle Biology and PhysiopathologyUniversity of PadovaPadovaItaly
  3. 3.Institute of NeurophysiologyUniversity of OsloOslo 1Norway