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Bell-shaped calcium-response curves of lns(l,4,5)P3- and calcium-gated channels from endoplasmic reticulum of cerebellum

Bell-shaped calcium-response curves of lns(l,4,5)P3- and calcium-gated channels from endoplasmic... RELEASE of calcium from intracellular stores occurs by two pathways, an inositol 1,4,5-trisphosphate (InsP3)-gated channel1–3 and a calcium-gated channel (ryanodine receptor)4–6. Using specific antibodies, both receptors were found in Purkinje cells of cerebellum7,8. We have now compared the functional properties of the channels corresponding to the two receptors by incorporating endoplasmic reticulum vesicles from canine cerebellum into planar bilayers. InsP3-gated channels were observed most frequently. Another channel type was activated by adenine nucleotides or caffeine, inhibited by ruthenium red, and modified by ryanodine, characteristics of the ryanodine receptor/channel6. The open probability of both channel types displayed a bell-shaped curve for dependence on calcium. For the InsP3-gated channel, the maximum probability of opening occurred at 0.2 µM free calcium, with sharp decreases on either side of the maximum. Maximum activity for the ryanodine receptor/channel was maintained between 1 and 100 µM calcium. Thus, within the physiological range of cytoplasmic calcium, the InsP3-gated channel itself allows positive feed-back and then negative feedback for calcium release, whereas the ryanodine receptor/channel behaves solely as a calcium-activated channel. The existence in the same cell of two channels with different responses to calcium and different ligand sensitivities provides a basis for complex patterns of intracellular calcium regulation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Springer Journals

Bell-shaped calcium-response curves of lns(l,4,5)P3- and calcium-gated channels from endoplasmic reticulum of cerebellum

Bezprozvanny, llya; Watras, James; Ehrlich, Barbara E.
Nature , Volume 351 (6329) – Jun 27, 1991
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References (32)

Publisher
Springer Journals
Copyright
Copyright © 1991 by Nature Publishing Group
Subject
Science, Humanities and Social Sciences, multidisciplinary; Science, Humanities and Social Sciences, multidisciplinary; Science, multidisciplinary
ISSN
0028-0836
eISSN
1476-4687
DOI
10.1038/351751a0
Publisher site
See Article on Publisher Site

Abstract

RELEASE of calcium from intracellular stores occurs by two pathways, an inositol 1,4,5-trisphosphate (InsP3)-gated channel1–3 and a calcium-gated channel (ryanodine receptor)4–6. Using specific antibodies, both receptors were found in Purkinje cells of cerebellum7,8. We have now compared the functional properties of the channels corresponding to the two receptors by incorporating endoplasmic reticulum vesicles from canine cerebellum into planar bilayers. InsP3-gated channels were observed most frequently. Another channel type was activated by adenine nucleotides or caffeine, inhibited by ruthenium red, and modified by ryanodine, characteristics of the ryanodine receptor/channel6. The open probability of both channel types displayed a bell-shaped curve for dependence on calcium. For the InsP3-gated channel, the maximum probability of opening occurred at 0.2 µM free calcium, with sharp decreases on either side of the maximum. Maximum activity for the ryanodine receptor/channel was maintained between 1 and 100 µM calcium. Thus, within the physiological range of cytoplasmic calcium, the InsP3-gated channel itself allows positive feed-back and then negative feedback for calcium release, whereas the ryanodine receptor/channel behaves solely as a calcium-activated channel. The existence in the same cell of two channels with different responses to calcium and different ligand sensitivities provides a basis for complex patterns of intracellular calcium regulation.

Journal

Nature – Springer Journals

Published: Jun 27, 1991

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