The influence of Lyn kinase on Na,K-ATPase in porcine lens epithelium

Larry D. Bozulic, William L. Dean, Nicholas A Delamere

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Abstract

Na,K-ATPase is essential for the regulation of cytoplasmic Na+ and K+ levels in lens cells. Studies on the intact lens suggest activation of tyrosine kinases may inhibit Na,K-ATPase function. Here, we tested the influence of Lyn kinase, a Src-family member, on tyrosine phosphorylation and Na,K-ATPase activity in membrane material isolated from porcine lens epithelium. Western blot studies indicated the expression of Lyn in lens cells. When membrane material was incubated in ATP-containing solution containing partially purified Lyn kinase, Na,K-ATPase activity was reduced by ∼38%. Lyn caused tyrosine phosphorylation of multiple protein bands. Immunoprecipitation and Western blot analysis showed Lyn treatment causes an increase in density of a 100-kDa phosphotyrosine band immunopositive for Na,K-ATPase α1 polypeptide. Incubation with protein tyrosine phosphatase 1B (PTP-1B) reversed the Lyn-dependent tyrosine phosphorylation increase and the change of Na,K-ATPase activity. The results suggest that Lyn kinase treatment of a lens epithelium membrane preparation is able to bring about partial inhibition of Na,K-ATPase activity associated with tyrosine phosphorylation of multiple membrane proteins, including the Na,K-ATPase α1 catalytic subunit.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume286
Issue number1 55-1
Publication statusPublished - Jan 2004
Externally publishedYes

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Keywords

  • Lens
  • Lyn
  • Na,K-ATPase
  • Tyrosine phosphorylation

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology

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