The influence of SRC-family tyrosine kinases on Na,K-ATPase activity in lens epithelium.
Invest Ophthalmol Vis Sci
; 46(2): 618-22, 2005 Feb.
Article
en En
| MEDLINE
| ID: mdl-15671290
ABSTRACT
PURPOSE:
Na,K-adenosine triphosphatase (ATPase) is essential for the regulation of cytoplasmic ion concentrations in lens cells. Earlier studies demonstrated that tyrosine phosphorylation by Lyn kinase, a Src-family member, inhibits Na,K-ATPase activity in porcine lens epithelium. In the present study, experiments were conducted to compare the ability of other Src-family kinases (Fyn, Src, and Lck) and Fes, a non-Src-family tyrosine kinase, to alter Na,K-ATPase activity.METHODS:
Membranes prepared from porcine lens epithelium were incubated with partially purified tyrosine kinases in buffer containing 1 mM adenosine triphosphate (ATP). ATP hydrolysis in the presence and absence of ouabain was used to measure Na,K-ATPase activity. Western blot analysis was used to examine phosphotyrosine-containing proteins and tyrosine kinase expression.RESULTS:
Fyn reduced Na,K-ATPase activity by approximately 30%. In contrast, Src caused a approximately 38% increase of Na,K-ATPase activity. Na,K-ATPase activity in membrane material treated with Lck or Fes was not significantly altered, even though Lck and Fes treatment induced robust tyrosine phosphorylation. Added exogenously, each tyrosine kinase induced a different pattern of membrane protein tyrosine phosphorylation. As judged by immunoprecipitation, Src, Fyn, Lyn, and Lck elicited tyrosine phosphorylation of the Na,K-ATPase alpha1 protein. Src, Fyn, Lyn, Lck, and Fes were each detectable in the epithelium by Western blot.CONCLUSIONS:
The results indicate considerable variation in the Na,K-ATPase activity response of lens epithelium to different tyrosine kinases. This could perhaps explain why inhibition of Na,K-ATPase activity is reported to be caused by tyrosine phosphorylation in some tissues, whereas stimulation of Na,K-ATPase activity is observed in other tissues.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
ATPasa Intercambiadora de Sodio-Potasio
/
Familia-src Quinasas
/
Cristalino
Límite:
Animals
Idioma:
En
Revista:
Invest Ophthalmol Vis Sci
Año:
2005
Tipo del documento:
Article
País de afiliación:
Estados Unidos