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Título
Ca2+ homeostasis in the endoplasmic reticulum measured with a new low-Ca2+-affinity targeted aequorin
Autor
Año del Documento
2013
Editorial
Elsevier Ltd.
Descripción
Producción Científica
Documento Fuente
Cell Calcium, 2013, vol. 54, p. 37-45
Abstract
We use here a new very low-Ca2+-affinity targeted aequorin to measure the [Ca2+] in the endoplasmic
reticulum ([Ca2+]ER). The new aequorin chimera has the right Ca2+-affinity to make long-lasting measurements
of [Ca2+]ER in the millimolar range. Moreover, previous Ca2+-depletion of the ER is no longer
required. The steady-state [Ca2+]ER obtained is 1–2 mM, higher than previously reported. In addition,
we find evidence that there is significant heterogeneity in [Ca2+]ER among different regions of the ER.
About half of the ER had a [Ca2+]ER of 1 mM or below, and the rest had [Ca2+]ER values above 1 mM and
in some parts even above 2 mM. About 5% of the ER was also found to have high [Ca2+]ER levels but to be
thapsigargin-insensitive and inositol trisphosphate insensitive. The rate of refilling with Ca2+ of the ER
was almost linearly dependent on the extracellular [Ca2+] between 0.1 and 3 mM, and was only partially
affected by mitochondrial membrane depolarization. Instead, it was significantly reduced by loading cells
with chelators, and the fast chelator BAPTA was much more effective than the slow chelator EGTA. This
suggests that local [Ca2+] microdomains connecting the store operated Ca2+ channels with the ER Ca2+
pumps may be important during refilling.
Materias (normalizadas)
Calcio en el organismo
ISSN
0143-4160
Revisión por pares
SI
Idioma
eng
Derechos
openAccess
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