Ca2+ Pumps in the Golgi Apparatus

In recent years, additionally to the well-characterized and intensively-studied plasma membrane Ca2+-ATPases (PMCAs) and sarco/endoplasmic reticulum Ca2+-ATPases (SERCAs), new P-type ATPases were identified, the secretory pathway Ca2+-ATPases (SPCAs) which are ion pumps that supply the lumen of the Golgi apparatus with divalent cations. For complete characterization of the human SPCA1 and SPCA2, our study focused on their cell type-specific expression, their distribution in intracellular organelles and their localization in cholesterol-rich membrane microdomains. The Golgi complex is believed to function as a releasable Ca2+ store, besides the major agonist-sensitive intracellular Ca2+ store the endoplasmic reticulum. Therefore, we investigated which part of the Golgi apparatus may contribution to the agonist-induced modulation of cytosolic Ca2+ concentration in human neutrophil granulocytes. In addition, the functional effects of Ca2+ release from the Golgi apparatus on neutrophil polarization and migration was studied.