a voltage-gated h+ channel underlying ph homeostasis in calcifying coccolithophores几种h +通道底层ph钙化颗石藻的动态平衡.pdfVIP

A Voltage-Gated H+ Channel Underlying pH Homeostasis in Calcifying Coccolithophores 1,2. 1. 1,3. 1 1 Alison R. Taylor , Abdul Chrachri , Glen Wheeler , Helen Goddard , Colin Brownlee * 1The Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, United Kingdom, 2 Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, United States of America, 3 Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, United Kingdom Abstract Marine coccolithophorid phytoplankton are major producers of biogenic calcite, playing a significant role in the global carbon cycle. Predicting the impacts of ocean acidification on coccolithophore calcification has received much recent attention and requires improved knowledge of cellular calcification mechanisms. Uniquely amongst calcifying organisms, coccolithophores produce calcified scales (coccoliths) in an intracellular compartment and secrete them to the cell surface, requiring large transcellular ionic fluxes to support calcification. In particular, intracellular calcite precipitation using HCO32 as the substrate generates equimolar quantities of H+ that must be rapidly removed to prevent cytoplasmic acidification. We have used electrophysiological approaches to identify a plasma membrane voltage-gated H+ conductance in Coccolithus pelagicus ssp braarudii with remarkably similar biophysical and functional properties to those found in metazoans. We show that both C. pelagicus and Emiliania huxleyi possess homologues of metazoan H + v 1 H channels, which functio