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Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation

We have observed the presence of membrane junctions formed between the plasma membrane and cortical endoplasmic reticulum of mature, unactivated eggs of xenopus laevis. The parallel, paired membranes of the junction are separated by a 10-mn gap within which electron-dense material is present. This m...

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Detalles Bibliográficos
Autores principales: Gardiner, DM, Grey, RD
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1983
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2112324/
https://www.ncbi.nlm.nih.gov/pubmed/6682118
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author Gardiner, DM
Grey, RD
author_facet Gardiner, DM
Grey, RD
author_sort Gardiner, DM
collection PubMed
description We have observed the presence of membrane junctions formed between the plasma membrane and cortical endoplasmic reticulum of mature, unactivated eggs of xenopus laevis. The parallel, paired membranes of the junction are separated by a 10-mn gap within which electron-dense material is present. This material occurs in patches with an average center-to-center distance of approximately 30 nm. These junctions are rare in immature (but fully grown) oocytes (approximately 2 percent of the plasma membrane is associated with junctions) and increase dramatically during progesterone-induced maturation. Junctions in the mature, unactivated egg are two to three times more abundant in the animal hemisphere (25-30 percent of the plasma membrane associated with junction) as compared with the vegetal hemisphere (10-15 percent). Junction density decreases rapidly to values characteristic of immature oocytes in response to egg activation. The plasma membrane-ER junctions of xenopus eggs are strikingly similar in structure to membrane junctions in muscle cells thought to be essential in the triggering of intracellular calcium release from the sarcoplasmic reticulum. In addition, the junctions’ distinctive, animal-vegetal polarity of distribution, their dramatic appearance during maturation, and their disapperance during activation are correlated with previously documented patterns of calcium-mediated events in anuran eggs. We discuss several lines of evidence supporting the hypothesis that these junctions in xenopus eggs are sites that transduce extracellular events into intracellular calcium release during fertilization and activation of development.
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spelling pubmed-21123242008-05-01 Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation Gardiner, DM Grey, RD J Cell Biol Articles We have observed the presence of membrane junctions formed between the plasma membrane and cortical endoplasmic reticulum of mature, unactivated eggs of xenopus laevis. The parallel, paired membranes of the junction are separated by a 10-mn gap within which electron-dense material is present. This material occurs in patches with an average center-to-center distance of approximately 30 nm. These junctions are rare in immature (but fully grown) oocytes (approximately 2 percent of the plasma membrane is associated with junctions) and increase dramatically during progesterone-induced maturation. Junctions in the mature, unactivated egg are two to three times more abundant in the animal hemisphere (25-30 percent of the plasma membrane associated with junction) as compared with the vegetal hemisphere (10-15 percent). Junction density decreases rapidly to values characteristic of immature oocytes in response to egg activation. The plasma membrane-ER junctions of xenopus eggs are strikingly similar in structure to membrane junctions in muscle cells thought to be essential in the triggering of intracellular calcium release from the sarcoplasmic reticulum. In addition, the junctions’ distinctive, animal-vegetal polarity of distribution, their dramatic appearance during maturation, and their disapperance during activation are correlated with previously documented patterns of calcium-mediated events in anuran eggs. We discuss several lines of evidence supporting the hypothesis that these junctions in xenopus eggs are sites that transduce extracellular events into intracellular calcium release during fertilization and activation of development. The Rockefeller University Press 1983-04-01 /pmc/articles/PMC2112324/ /pubmed/6682118 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Articles
Gardiner, DM
Grey, RD
Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
title Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
title_full Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
title_fullStr Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
title_full_unstemmed Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
title_short Membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
title_sort membrane junctions in xenopus eggs: their distribution suggests a role in calcium regulation
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2112324/
https://www.ncbi.nlm.nih.gov/pubmed/6682118
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