Calcium uniporter

Kirichok, Y., Krapivinsky, G. and Clapham, D. E., 2004, The mitochondrial calcium uniporter is a highly selective ion channel. Nature 427, 360-4. 

Fig. 2.5. Interaction of Ca transport with the proton circuit, a, Ca uptake alone discharges the membrane potential b, Ca uptake in exchange for protons extruded by the respiratory chain generates a pH gradient c, Ca uptake together with a weak acid such as acetate does not build up a pH gradient d, Ca cycling in heart mitochondria driven by the proton circuit. R, respiratory chain C, calcium uniport NH, sodium/proton antiport NC, sodium/calcium antiport.

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