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Inhibition of serin...
Inhibition of serine/threonine protein phosphatases promotes opening of voltage-activated L-type Ca2+ channels in insulin-secreting cells
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Haby, Christelle (författare)
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Larsson, Olof (författare)
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- Islam, M. Shahidul (författare)
- Uppsala universitet,Medicin
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visa fler...
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Aunis, Dominique (författare)
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Berggren, Per-Olof (författare)
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Zwiller, Jean (författare)
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visa färre...
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(creator_code:org_t)
- 1994
- 1994
- Engelska.
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 298:Pt 2, s. 341-346
- Relaterad länk:
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https://urn.kb.se/re...
Abstract
Ämnesord
Stäng
- The biological activity of many proteins, including voltage-sensitive ion channels, is controlled by their state of phosphorylation. Ca2+ influx through voltage-activated L-type Ca2+ channels serves as the major stimulatory signal in insulin-secreting cells. We have now investigated the extent to which Ca2+ handling in clonal insulin-secreting RiNm5F cells was affected by okadaic acid, an inhibitor of various serine/threonine protein phosphatases. Whole-cell patch-clamp experiments showed that okadaic acid generated an increase in membrane current, suggesting that it promotes Ca2+ influx through L-type voltage-gated Ca2+ channels probably by modifying their phosphorylation state. Okadaic acid was found to provoke a transient rise in the cytoplasmic free Ca2+ concentration ([Ca2+]i) but had no further effect on the K(+)-induced increase. The Ca2+ transient induced by okadaic acid was dependent on the presence of extracellular Ca2+ and was abolished by D600, a blocker of voltage-activated L-type Ca2+ channels. Concomitant with the rise in [Ca2+]i, okadaic acid induced insulin secretion, a phenomenon that was also dependent on extracellular Ca2+. It is proposed that hyperphosphorylation of voltage-activated L-type Ca2+ channels in insulin-secreting cells lowers the threshold potential for their activation.
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- MEDICINE
- MEDICIN
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