CA-ATPASE AND BONE CELL MINERALIZATION

The plasma membrane Ca-ATPases play an important role in the regulatio n of intracellular Ca2+ ion concentration by pumping Ca2+ out of the c ell into the extracellular fluid al the expense of Am. These pumps pot entially play an important role in the delivery of Ca2+ during mineral ization of hard tissues such as bone, The properties of the plasma mem brane Ca2+ pump are compared with those of the sarco(endo)plasmic reti culum and the factors regulating pump function are presented. The diff erent gene products for the plasma membrane Ca-ATPases are described a s well as their known functional significance. Particular attention is paid to the plasma membrane Ca2+ pumps present in mineralizing tissue s and evidence supporting a role for these pumps in the transcellular delivery of Ca2+ during the process of mineralization is also presente d.