Archives of Toxicology

, Volume 64, Issue 6, pp 490–496

Activation of troponin C by Cd2+ and Pb2+

  • ShengHao Chao
  • Chun -Hui Bu
  • Wai Yiu Cheung
Article

DOI: 10.1007/BF01977632

Cite this article as:
Chao, S., Bu, C.H. & Cheung, W.Y. Arch Toxicol (1990) 64: 490. doi:10.1007/BF01977632

Abstract

Certain heavy metal actions such as Cd2+ and Pb2+ mimic Ca2+ effectively in stimulating calmodulin (CaM). We now show that these cations also activate skeletal muscle troponin C (TnC), a Ca2+-binding protein highly homologous to CaM. Like Ca2+, these cations allow TnC to alter its electrophoretic mobility on polyacrylamide gels, and to bind to phenyl-Sepharose. Moreover, they activate TnC to stimulate myofibrillar ATPase. When TnC was removed from the skeletal myofibrils by treatment with trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid (CDTA), the ATPase activity was no longer stimulated by the cations. However, after reconstitution of CDTA-treated skeletal myofibril with TnC, the response of ATPase to Ca2+, Cd2+ or Pb2+ was restored. These findings suggest that the activation of myofibrillar ATPase by Cd2+ and Pb2+ is mediated through TnC. The ability of the heavy metals to stimulate TnC-supported ATPase activity correlated quite well with the ability to increase the extent of the myofibrillar superprecipitation. The activation of TnC by Cd2+ or Pb2+ could constitute a possible molecular basis for their toxicity.

Key words

Troponin C Cadmium Lead Myofibrillar ATPase Heavy metal toxicity 

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • ShengHao Chao
    • 1
  • Chun -Hui Bu
    • 1
  • Wai Yiu Cheung
    • 1
    • 2
  1. 1.Department of BiochemistrySt. Jude Children's Research HospitalMemphisUSA
  2. 2.Department of BiochemistryUniversity of TennesseeMemphisUSA

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