%0 Journal Article
%T A pH-correctable, DNA-based fluorescent reporter for organellar calcium
%J -
%D 2018
%R https://doi.org/10.1038/s41592-018-0232-7
%X It is extremely challenging to quantitate lumenal Ca2+ in acidic Ca2+ stores of the cell because all Ca2+ indicators are pH sensitive, and Ca2+ transport is coupled to pH in acidic organelles. We have developed a fluorescent DNA-based reporter, CalipHluor, that is targetable to specific organelles. By ratiometrically reporting lumenal pH and Ca2+ simultaneously, CalipHluor functions as a pH-correctable Ca2+ reporter. By targeting CalipHluor to the endolysosomal pathway, we mapped lumenal Ca2+ changes during endosomal maturation and found a surge in lumenal Ca2+ specifically in lysosomes. Using lysosomal proteomics and genetic analysis, we found that catp-6, a Caenorhabditis elegans homolog of ATP13A2, was responsible for lysosomal Ca2+ accumulation¡ªan example of a lysosome-specific Ca2+ importer in animals. By enabling the facile quantification of compartmentalized Ca2+, CalipHluor can expand the understanding of subcellular Ca2+ importers
%U https://www.nature.com/articles/s41592-018-0232-7