Ca(2+) signalling in the Golgi apparatus

The Golgi apparatus plays a central role in lipid and protein post-translational modification and sorting. Morphologically the organelle is heterogeneous and it is possible to distinguish stacks of flat cysternae (cis- and medial Golgi), tubular-reticular networks and vesicles (trans-Golgi). These morphological differences parallel a distinct functionality with a selective distribution and complementary roles of the enzymes found in the different compartments.The Golgi apparatus has been also shown to be involved in Ca²⁺ signalling: it is indeed endowed with Ca²⁺ pumps, Ca²⁺ release channels and Ca²⁺ binding proteins and is thought to participate in determining the spatio-temporal complexity of the Ca²⁺ signal within the cell, though this role is still poorly understood.Recently, it has been demonstrated that the organelle is heterogeneous in terms of Ca²⁺ handling and selective reduction of Ca²⁺ concentration, both in vitro and in a genetic human disease, within one of its sub-compartment results in alterations of protein trafficking within the secretory pathway and of the entire Golgi morphology.In this paper we review the available information on the Ca²⁺ toolkit within the Golgi, its heterogeneous distribution in the organelle sub-compartments and discuss the implications of these characteristics for the physiopathology of the Golgi apparatus.