Figures & data
Figure 1 Ca2+ concentration and molecular tool-kit gradient through the secretory pathway. The endoplasmic reticulum (ER) is endowed with SERCA, IP3Rs and, in some cells, RyRs and its luminal [Ca2+] is estimated to be around 400 µM. The Golgi apparatus (GA) can be divided in three distinct sub-compartments: the cis-Golgi, with a luminal [Ca2+] around 250 µM and expressing mainly SERCA and IP3Rs; the medial-Golgi with SERCA and SPCA1, but not with IP3Rs; the trans-Golgi with SPCA1 and RyRs (but not IP3Rs) and a luminal [Ca2+] of ∼130 µM. Finally, secretory vesicles (SV) are endowed with SPCA1 and RyRs and show a [Ca2+] around 80 µM. TGN, trans-Golgi network. This model is based on quantitative data for the ER and GA obtained in HeLa cells,Citation7,Citation14,Citation15 while the data on the secretory vesicles have been extrapolated from experiments carried out in insulin secreting cells.Citation17
![Figure 1 Ca2+ concentration and molecular tool-kit gradient through the secretory pathway. The endoplasmic reticulum (ER) is endowed with SERCA, IP3Rs and, in some cells, RyRs and its luminal [Ca2+] is estimated to be around 400 µM. The Golgi apparatus (GA) can be divided in three distinct sub-compartments: the cis-Golgi, with a luminal [Ca2+] around 250 µM and expressing mainly SERCA and IP3Rs; the medial-Golgi with SERCA and SPCA1, but not with IP3Rs; the trans-Golgi with SPCA1 and RyRs (but not IP3Rs) and a luminal [Ca2+] of ∼130 µM. Finally, secretory vesicles (SV) are endowed with SPCA1 and RyRs and show a [Ca2+] around 80 µM. TGN, trans-Golgi network. This model is based on quantitative data for the ER and GA obtained in HeLa cells,Citation7,Citation14,Citation15 while the data on the secretory vesicles have been extrapolated from experiments carried out in insulin secreting cells.Citation17](/cms/asset/78cb4e05-2b3e-43a4-ba01-a18bff5a89eb/kcib_a_10912473_f0001.gif)