Ca-ATPase and bone cell mineralization.

The plasma membrane Ca-ATPases play an important role in the regulation of intracellular Ca2+ ion concentration by pumping Ca2+ out of the cell into the extracellular fluid at the expense of ATP. These pumps potentially play an important role in the delivery of Ca2+ during mineralization of hard tissues such as bone. The properties of the plasma membrane Ca2+ pump are compared with those of the sarco(endo)plasmic reticulum and the factors regulating pump function are presented. The different gene products for the plasma membrane Ca-ATPases are described as well as their known functional significance. Particular attention is paid on the plasma membrane Ca2+ pumps present in mineralizing tissues and evidence supporting a role for these pumps in the transcellular delivery of Ca2+ during the process of mineralization is also presented.