Table 1.
Ca2+ transport into acidic stores
| Calcium pump/exchanger | General characteristics | Associated Human Genetic Diseases | Acidic store |
|---|---|---|---|
| PMCA-type Ca2+-ATPase (subgroup IIB) | P-type, 10 TMD Ca2+ transport in exchange for H+ One Ca2+ binding site |
Hereditary deafness (PMCA2) | Acidocalcisomes [6] Yeast vacuole [12] Dictyostelium contractile vacuole [11] Plant vacuole [80] |
| SERCA-type Ca2+-ATPase (subgroup IIA) | P-type, 10 TMD Ca2+ transport in exchange for H+ Two Ca2+ binding sites Specific inhibition by thapsigargin and cyclopiazonic acid |
Brody s disease (SERCA1) Darier-White s disease (SERCA2) |
Lysosome-related organelles [83, 84] Secretory granules [35, 37, 82] Golgi apparatus [81] |
| SPCA-type Ca2+-ATPase (subgroup IIA) | P-type, 10 TMD Ca2+ and Mn2+ transport One Ca2+/Mn2+ binding site |
Hailey-Hailey s disease (SPCA1) | Secretory granules [36] Golgi apparatus [81] |
| Unidentified Ca2+-ATPase | P-type, ND Ca2+ transport |
ND | Lysosomes [86–88] Synaptic vesicles [89] |
| Ca2+/H+ exchanger (CAX) | 11 TMD (two “half-proteins” separated by an “acidic motif”) Reversible | ND | Acidocalcisomes [6] Yeast vacuole [91] Plant vacuole [92] Melanosomes# [93] Secretory granules# [37] Synaptic vesicles# [89] |
| Na+/Ca2+ exchanger (NCX) | 11 TMD, Ca2+ exchange for Na+ Reversible | ND | Secretory granules# [37, 94] Melanosomes (NCKX5) [71] |
#
The molecular identity of the exchanger is unknown. ND, not determined; P-type: characterized by the formation of a phosphorylated enzyme intermediate, and inhibited by vanadate; TMD, transmembrane domains; NCKX5, potassium-dependent Na2+/Ca2+ exchanger