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Coexpression and stimulation of parathyroid hormone receptor positively regulates slowly activating IsK channels expressed in Xenopus oocytes.


Waldegger, S; Raber, G; Sussbrich, H; Ruppersberg, J P; Fakler, B; Murer, H; Lang, F; Busch, A E (1996). Coexpression and stimulation of parathyroid hormone receptor positively regulates slowly activating IsK channels expressed in Xenopus oocytes. Kidney International, 49(1):112-116.

Abstract

Expression of the IsK protein in Xenopus oocytes induced the characteristically slow, voltage-dependent outward currents. Superfusion with the parathyroid hormone (PTH) peptide 1-34 had no effect on IsK when expressed alone, but increased IsK when IsK was coexpressed with the PTH-receptor. PTH receptor stimulation caused a shift of IsK conductance-voltage relationship to more negative potentials, and a decrease of both the rate of IsK activation and deactivation. IsK regulation by PTH was independent of extracellular Ca2+, and was also present IsK protein mutants lacking the protein kinase C consensus site. However, regulation of IsK by PTH was mimicked by activators of protein kinase A (PKA) and greatly reduced in the presence of the kinase inhibitors staurosporine and H89. These results suggest that PTH regulates IsK by a mechanism involving phosphorylation independent of protein kinase C (PKC). Such regulation may play a role in proximal tubule cells of the kidney, where both PTH receptor and the IsK protein are expressed.

Expression of the IsK protein in Xenopus oocytes induced the characteristically slow, voltage-dependent outward currents. Superfusion with the parathyroid hormone (PTH) peptide 1-34 had no effect on IsK when expressed alone, but increased IsK when IsK was coexpressed with the PTH-receptor. PTH receptor stimulation caused a shift of IsK conductance-voltage relationship to more negative potentials, and a decrease of both the rate of IsK activation and deactivation. IsK regulation by PTH was independent of extracellular Ca2+, and was also present IsK protein mutants lacking the protein kinase C consensus site. However, regulation of IsK by PTH was mimicked by activators of protein kinase A (PKA) and greatly reduced in the presence of the kinase inhibitors staurosporine and H89. These results suggest that PTH regulates IsK by a mechanism involving phosphorylation independent of protein kinase C (PKC). Such regulation may play a role in proximal tubule cells of the kidney, where both PTH receptor and the IsK protein are expressed.

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Additional indexing

Item Type:Journal Article, refereed
Communities & Collections:04 Faculty of Medicine > Institute of Physiology
07 Faculty of Science > Institute of Physiology
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Date:1 January 1996
Deposited On:11 Feb 2008 12:22
Last Modified:05 Apr 2016 12:18
Publisher:Nature Publishing Group
ISSN:0085-2538
Publisher DOI:10.1038/ki.1996.15
PubMed ID:8770956

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