Abstract
Ca(2+) is an important intracellular messenger affecting diverse cellular processes. In eukaryotic cells, Ca(2+) is handled by a myriad of Ca(2+)-binding proteins found in organelles that are organized into the cellular reticular network (CRN). The network is comprised of the endoplasmic reticulum, Golgi apparatus, lysosomes, membranous components of the endocytic and exocytic pathways, peroxisomes, and the nuclear envelope. Membrane contact sites between the different components of the CRN enable the rapid movement of Ca(2+), and communication of Ca(2+) status, within the network. Ca(2+)-handling proteins that reside in the CRN facilitate Ca(2+) sensing, buffering, and cellular signaling to coordinate the many processes that operate within the cell.