Lack of tropomyosin correlates with the absence of stress fibers in transformed rat kidney cells

C. L. Leonardi, R. H. Warren, R. W. Rubin

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


We have utilized epithelial rat kidney cells and their Kirsten viral transformant (442) to examine the role of actin-binding proteins in cellular morphogenesis. Normal rat kidney cells are well spread while the transformed cells are more spherical, poorly adherent, and lack actin stress fibers (Rubin, R.W., Warren, R.H., Lukeman, D.S. and Clements, E. (1978) J. Cell Biol. 78, 28-35). By immunofluorescence, anti-tropomyosin prominently stains normal rat kidney cell stress fibers while only a weak, nonspecific fluorescence is observed in 442 cells. Using two-dimensional gel electrophoresis, tropomyosin can be detected in normal rat kidney cell homogenates. The tropomyosin subunits are enriched in Triton-extracted filamentous normal rat kidney cell models, and in extracts of normal rat kidney cell homogenate produced by using a rapid myosin affinity technique to isolate actin and actin-associated proteins. The identity of the tropomyosin subunits has been confirmed by electrophoretic mobility, lack of proline, and the peptide map generated by limited proteolysis. None of these techniques have detected tropomyosin in the corresponding 442 preparations. Our results suggest that transformation of normal rat kidney cells has led to an overall reduction in tropomyosin content. This may be related to the inability of 442 cells to organize filamentous actin stress fibers.

Original languageEnglish (US)
Pages (from-to)154-162
Number of pages9
JournalBBA - Molecular Cell Research
Issue number2
StatePublished - Apr 29 1982


  • (Rat kidney)
  • Stress fiber
  • Transformation
  • Tropomyosin

ASJC Scopus subject areas

  • Biophysics
  • Cell Biology
  • Molecular Biology
  • Medicine(all)


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