Activation of neuroendocrine L-type channels (alpha1D subunits) in retinal pigment epithelial cells and brain neurons by pp60(c-src)

The aim of this study is to characterize the subtype of tyrosine kinase-regulated L-type Ca(2+) channels in retinal pigment epithelial (RPE) cells. Ca(2+) channel alpha1D-subunits were enriched by immunoprecipitation from membrane proteins isolated from rat RPE cells. Western blot analysis of the pr...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2000-04, Vol.270 (3), p.806-810
Main Authors: Strauss, O, Buss, F, Rosenthal, R, Fischer, D, Mergler, S, Stumpff, F, Thieme, H
Format: Article
Language:English
Subjects:
Animals
Antibodies - pharmacology
Brain - physiology
Calcium Channels, L-Type - isolation & purification
Calcium Channels, L-Type - physiology
Cell Membrane - physiology
Cells, Cultured
Membrane Potentials - physiology
Membrane Proteins - isolation & purification
Membrane Proteins - metabolism
Neurons - physiology
Patch-Clamp Techniques
Pigment Epithelium of Eye - physiology
pp60 protein
Proto-Oncogene Proteins pp60(c-src) - isolation & purification
Proto-Oncogene Proteins pp60(c-src) - metabolism
Rats
retinal pigment epithelium
Src protein
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Summary:The aim of this study is to characterize the subtype of tyrosine kinase-regulated L-type Ca(2+) channels in retinal pigment epithelial (RPE) cells. Ca(2+) channel alpha1D-subunits were enriched by immunoprecipitation from membrane proteins isolated from rat RPE cells. Western blot analysis of the precipitates revealed coprecipitation of pp60(c-src). In addition, in precipitates obtained with antibodies against pp60(c-src), alpha1D-subunits were identified. The same was observed in immunoprecipitations from rat brain neurons. Tyrosine phosphorylation of alpha1D-subunits was confirmed using anti-phosphotyrosine antibodies. Ba(2+) currents through L-type channels in cultured rat RPE cells were increased by intracellular application of active pp60(c-src) (30 U/ml) (heat-inactivated pp60(c-src) had no effect). Thus, L-type channels of the neuroendocrine subtype can be expressed in epithelial cells and are activated by tyrosine kinase of the src subtype. This kind of regulation is also suggested for brain-derived neurons.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.2000.2513