| Comments |
P.77 legend to figure 4a: "The ER [endoplasmic reticulum] lumen is the major Ca2+ store in the cell, with a Ca2+ concentration ([Ca2+]) of ~60–500 μM). In the extracellular space, [Ca2+] is high (~1mM) compared to the intracellular cytosol (~100nM). Newly formed endosomes have taken up Ca2+ from the extracellular space, so the luminal [Ca2+] is close to the same as that of the extracellular space (~1 mM). Luminal Ca2+ is then released so that early endosomes have [Ca2+] ~0.5 μM and late endosomes have [Ca2+] ~2.5 μM. The ER–endosome MCS [membrane contact sites] is a site of dynamic Ca2+ crosstalk. Endosomes may be able to sequester Ca2+ released from the ER. The ER transfers Ca2+ to mitochondria, with peak mitochondrial Ca2+ concentrations reaching 100 μM." Note-extracellular and newly formed endosome concentrations of Ca2+ are ~1mM (as in legend to figure and not as in figure) |