AXER is an ATP/ADP exchanger in the membrane of the endoplasmic reticulum

Nat Commun. 2018 Aug 28;9(1):3489. doi: 10.1038/s41467-018-06003-9.

Marie-Christine Klein ¹, Katharina Zimmermann ², Stefan Schorr ¹, Martina Landini ³, Patrick A W Klemens ³, Jacqueline Altensell ³, Martin Jung ¹, Elmar Krause ⁴, Duy Nguyen ⁵, Volkhard Helms ⁵, Jens Rettig ⁴, Claudia Fecher-Trost ⁶, Adolfo Cavalié ⁶, Markus Hoth ², Ivan Bogeski ⁷ ⁸, H Ekkehard Neuhaus ⁹, Richard Zimmermann ¹⁰, Sven Lang ¹, Ilka Haferkamp ³

Affiliations

1 Medical Biochemistry and Molecular Biology, Saarland University, 66421, Homburg, Germany.
2 Biophysics, CIPMM Saarland University, 66421, Homburg, Germany.
3 Plant Physiology, Technical University Kaiserslautern, 67663, Kaiserslautern, Germany.
4 Physiology, CIPMM Saarland University, 66421, Homburg, Germany.
5 Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany.
6 Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421, Homburg, Germany.
7 Biophysics, CIPMM Saarland University, 66421, Homburg, Germany. ivan.bogeski@med.uni-goettingen.de.
8 Molecular Physiology, University Medical Center, University of Göttingen, 37073, Göttingen, Germany. ivan.bogeski@med.uni-goettingen.de.
9 Plant Physiology, Technical University Kaiserslautern, 67663, Kaiserslautern, Germany. neuhaus@rhrk.uni-kl.de.
10 Medical Biochemistry and Molecular Biology, Saarland University, 66421, Homburg, Germany. richard.zimmermann@uks.eu.

PMID: 30154480 DOI: 10.1038/s41467-018-06003-9

Abstract

To fulfill its role in protein biogenesis, the endoplasmic reticulum (ER) depends on the Hsp70-type molecular chaperone BiP, which requires a constant ATP supply. However, the carrier that catalyzes ATP uptake into the ER was unknown. Here, we report that our screen of gene expression datasets for member(s) of the family of solute carriers that are co-expressed with BiP and are ER membrane proteins identifies SLC35B1 as a potential candidate. Heterologous expression of SLC35B1 in E. coli reveals that SLC35B1 is highly specific for ATP and ADP and acts in antiport mode. Moreover, depletion of SLC35B1 from HeLa cells reduces ER ATP levels and, as a consequence, BiP activity. Thus, human SLC35B1 may provide ATP to the ER and was named AXER (ATP/ADP exchanger in the ER membrane). Furthermore, we propose an ER to cytosol low energy response regulatory axis (termed lowER) that appears as central for maintaining ER ATP supply.

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