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Inhibition of serin...
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Haby, Christelle
(author)
Inhibition of serine/threonine protein phosphatases promotes opening of voltage-activated L-type Ca2+ channels in insulin-secreting cells
- Article/chapterEnglish1994
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LIBRIS-ID:oai:DiVA.org:uu-132298
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https://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-132298URI
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Language:English
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Summary in:English
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Subject category:ref swepub-contenttype
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Subject category:art swepub-publicationtype
Notes
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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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Larsson, Olof
(author)
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Islam, M. ShahidulUppsala universitet,Medicin
(author)
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Aunis, Dominique
(author)
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Berggren, Per-Olof
(author)
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Zwiller, Jean
(author)
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Uppsala universitetMedicin
(creator_code:org_t)
Related titles
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In:Biochemical Journal298:Pt 2, s. 341-3460264-60211470-8728
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