An otopetrin family proton channel promotes cellular acid efflux critical for biomineralization in a marine calcifier
William Chang, Ann-Sophie Matt, Marcus Schewe, Marianne Musinszki, Sandra Grüssel, Jonas Brandenburg, David Garfield, Markus Bleich, Thomas Baukrowitz, Marian Y. Hu
Abstract
Significance Otopetrins comprise a family of proton channels that are required for the development of calcified structures including otoliths and statoconia in vertebrates. To date, it remains unknown how otopetrins contribute to the calcification process. Using the sea urchin larva, we could demonstrate that the otopetrin ortholog otop2l encodes a proton channel that is essential for the formation of the CaCO 3 skeleton. otop2l is exclusively expressed by the calcifying primary mesenchyme cells, where it promotes the exit of protons liberated by the mineralization process. Given the deep phylogenetic origin of otopetrins in animals, our work identified a key mechanism in the mineralization process with relevance for many calcifying species and their responses to changes in environmental pH.