High Ca2+ content in the Golgi apparatus (Go) is essential for protein processing and sorting. In addition, the Go can shape the cytosolic Ca2+ signals by releasing or sequestering Ca2+. We generated two new aequorin-based Ca2+ probes to specifically measure Ca2+ in the cis/cis-to-medial-Go (cGo) or the trans-Go (tGo). Ca2+ homoeostasis in these compartments and in the endoplasmic reticulum (ER) has been studied and compared. Moreover, the relative size of each subcompartment was estimated from aequorin consumption. We found that the cGo accumulates Ca2+ to high concentrations (150–300 μM) through the sarco plasmic/endoplasmic reticulum Ca2+-ATPase (SERCA). The tGo, in turn, is divided into two subcompartments: tGo1 and tGo2. The subcompartment tGo1 contains 20% of the aequorin and has a high internal [Ca2+]; Ca2+ is accumulated in this subcompartment via the secretory pathway Ca2+-ATPase 1 (SPCA-1) at a very high affinity (K50=30 nM). The subcompartment tGo2 contains 80% of aequorin, has a lower [Ca2+] and no SPCA-1 activity; Ca2+ uptake happens through SERCA and is slower than in tGo1. The two tGo subcompartments, tGo1 and tGo2, are diffusionally isolated. Inositol trisphosphate mobilizes Ca2+ from the cGo and tGo2, but not from tGo1, whereas caffeine releases Ca2+ from all the Golgi regions, and nicotinic acid dinucleotide phosphate and cADP ribose from none.
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Research Article|
March 06 2015
Differential calcium handling by the cis and trans regions of the Golgi apparatus
Francisco J. Aulestia;
Francisco J. Aulestia
*Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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María Teresa Alonso;
María Teresa Alonso
*Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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Javier García-Sancho
Javier García-Sancho
1
*Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
1To whom correspondence should be addressed (email jgsancho@ibgm.uva.es).
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Publisher: Portland Press Ltd
Received:
November 05 2014
Revision Received:
December 15 2014
Accepted:
December 16 2014
Accepted Manuscript online:
December 16 2014
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2015 Biochemical Society
2015
Biochem J (2015) 466 (3): 455–465.
Article history
Received:
November 05 2014
Revision Received:
December 15 2014
Accepted:
December 16 2014
Accepted Manuscript online:
December 16 2014
Citation
Francisco J. Aulestia, María Teresa Alonso, Javier García-Sancho; Differential calcium handling by the cis and trans regions of the Golgi apparatus. Biochem J 15 March 2015; 466 (3): 455–465. doi: https://doi.org/10.1042/BJ20141358
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