Voltage-gated Ca2+ channel density in excitable cell membranes

Range ~100 channels/µm^2
Organism Eukaryotes
Reference Kirichok Y, Krapivinsky G, Clapham DE. The mitochondrial calcium uniporter is a highly selective ion channel. Nature. 2004 Jan 22 427(6972):360-4. doi:10.1038/nature02246 p.363 left column 2nd paragraphPubMed ID14737170
Primary Source Hille, B. Ion Channels of Excitable Membranes (Sinauer Associates, Sunderland, Massachusetts, 2001).
Method "[Researchers] patch-clamp single mitoplasts (2–5µm vesicles of inner mitochondrial membrane) isolated from COS-7 cells (Fig. 1a, b), to measure directly whole-mitoplast and single-channel Ca2+ currents."
Comments "...unlike many Ca2+ -selective currents, I(MiCa) [mitochondrial calcium] lacked Ca2+ -dependent inactivation at energized mitochondrial potentials (approximately -160 mV)...On the basis of an I(MiCa) density of 1,000–2,000 pA/pF, >90% open probability, and 0.5–1 pA single-channel amplitude at [Ca2+]c=105mM and Vm=-160mV, MiCa channel density in the inner mitochondrial membrane is approximately 10–40 channels per µm^2, slightly lower than voltage-gated Ca2+ channel density (about 100 per µm^2) (primary source) in excitable cell membranes."
Entered by Uri M
ID 110627