part_of calcium homeostasis pathway metal ion transport pathway calcium transport pathway 2012-11-05T09:59:28Z Calcium is pumped into organelles or out of the cell by pumps and exchangers to maintain the low calcium concentration necessary for cell viability. Many type of channels, some calcium-selective, others of lower selectivity or calcium-permeant, allow for the flow of calcium from external sources or internal stores into the cell to initiate many signaling events. The movement of calcium ions, which controls and maintains the calcium gradient, and calcium signaling, which the gradient promotes, are inextricably connected in the fabric of calcium homeostasis. PW:0001139 calcium ion transport pathway vpetri