'Trigger' events precede calcium puffs in Xenopus oocytes.

'Trigger' events precede calcium puffs in Xenopus oocytes. Research Abstract Details 

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'Trigger' events precede calcium puffs in Xenopus oocytes. Abstract Text:

Heather J Rose,Sheila Dargan,Jianwei Shuai,Ian Parker,

The liberation of calcium ions sequestered in the endoplasmic reticulum through inositol 1,4,5-trisphosphate receptors/channels (IP(3)Rs) results in a spatiotemporal hierarchy of calcium signaling events that range from single-channel openings to local Ca(2+) puffs believed to arise from several to tens of clustered IP(3)Rs to global calcium waves. Using high-resolution confocal linescan imaging and a sensitive Ca(2+) indicator dye (fluo-4-dextran), we show that puffs are often preceded by small, transient Ca(2+) elevations that we christen "trigger events". The magnitude of triggers is consistent with their arising from the opening of a single IP(3) receptor/channel, and we propose that they initiate puffs by recruiting neighboring IP(3)Rs within the cluster by a regenerative process of Ca(2+)-induced Ca(2+) release. Puff amplitudes (fluorescence ratio change) are on average approximately 6 times greater than that of the triggers, suggesting that at least six IP(3)Rs may simultaneously be open during a puff. Trigger events have average durations of approximately 12 ms, as compared to 19 ms for the mean rise time of puffs, and their spatial extent is approximately 3 times smaller than puffs (respective widths at half peak amplitude 0.6 and 1.6 micro m). All these parameters were relatively independent of IP(3) concentration, although the proportion of puffs showing resolved triggers was greatest (approximately 80%) at low [IP(3)]. Because Ca(2+) puffs constitute the building blocks from which cellular IP(3)-mediated Ca(2+) signals are constructed, the events that initiate them are likely to be of fundamental importance for cell signaling. Moreover, the trigger events provide a useful yardstick by which to derive information regarding the number and spatial arrangement of IP(3)Rs within clusters.

'Trigger' events precede calcium puffs in Xenopus oocytes. Publishing Authors By Initials

HJ Rose,S Dargan,J Shuai,I Parker,

For similar animals: chordata: vertebrates: amphibia: anura: pipidae: xenopus: xenopus laevis research abstracts see: animals: chordata: vertebrates: amphibia: anura: pipidae: xenopus: xenopus laevis research

PUBMED ID PMID:

MEDLINE DATE:

'Trigger' events precede calcium puffs in Xenopus oocytes. Journal Published:

PUBLICATION TYPE: Research Support, N.I.H., Extr

Journal: Biophysical journal

VOLUME: 91

Page Numbers: 4024-32

Journal Abbreviation: Biophys. J.

ISSN: 0006-3495

DAY: 15

MONTH: 09

YEAR: 2006

'Trigger' events precede calcium puffs in Xenopus oocytes. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 370626

'Trigger' events precede calcium puffs in Xenopus oocytes. Keywords Mesh Terms:

KEYWORDS: Xenopus laevis

MESH TERMS: metabolism

Chemical & Substance for Abstract: 'Trigger' events precede calcium puffs in Xenopus oocytes. Information

Substance Name: Dextrans

Registry Number: 9004-54-0

Grant and Affiliation Information for 'Trigger' events precede calcium puffs in Xenopus oocytes.

AFFILIATION: Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, USA. heather@uci.edu

Country: United States

AGENCY: United States NIGMS

GRANT: GM 65830

ACRONYM: GM

MEDLINETA: Biophys J

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