Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Groschner, K; Schuhmann, K; Mieskes, G; Baumgartner, W; Romanin, C.
A type 2A phosphatase-sensitive phosphorylation site controls modal gating of L-type Ca2+ channels in human vascular smooth-muscle cells.
Biochem J. 1996; 318 ( Pt 2)(4):513-517
Doi: 10.1042/bj3180513
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- Groschner Klaus
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- Abstract:
- The patch-clamp technique was employed to investigate phosphorylation/dephosphorylation-dependent modulation of L-type Ca2+ channels in smooth-muscle cells isolated from human umbilical vein. Okadaic acid, an inhibitor of phosphoprotein phosphatases type 1 (PP1) and 2A (PP2A), increased the probability of channels being in the open state (Po) in intact cells. This increase in Po was due mainly to promotion of long-lasting channel openings, i.e. promotion of 'mode 2' gating behaviour. Exposure of the cytoplasmic side of excised patches of membrane to the purified catalytic subunit of PP2A (PP2Ac) resulted in the opposite modulation of channel function. PP2Ac (0.2 unit/ml) reduced the Po of Ca2+ channels mainly via suppression of 'mode 2' gating. This effect of PP2Ac was completely prevented by 1 microM okadaic acid. The catalytic subunit of PPI (0.2 unit/ml), however, barely affected channel activity. Our results provide evidence for a PP2A-sensitive regulatory site that controls modal gating of L-type Ca2+ channels in smooth muscle.
- Find related publications in this database (using NLM MeSH Indexing)
- Calcium Channels - drug effects Calcium Channels - physiology
- Calcium Channels, L-Type -
- Enzyme Inhibitors - pharmacology
- Humans -
- Ion Channel Gating -
- Kinetics -
- Models, Biological -
- Muscle, Smooth, Vascular - physiology
- Okadaic Acid - pharmacology
- Patch-Clamp Techniques -
- Phosphoprotein Phosphatases - antagonists and inhibitors Phosphoprotein Phosphatases - metabolism
- Phosphorylation -
- Time Factors -
- Umbilical Veins - physiology