A high affinity Ca2+-ATPase in enriched nerve-ending plasma membranes.

A preparation of enriched synaptosomal plasma membrane (SPM) from mouse brain was found to contain a Mg2+-independent high affinity Ca2+-activated ATPase. The preparation readily accumulated Ca2+ at micromolar concentration from the medium in the presence or absence of Mg2+ and released previously accumulated calcium upon the addition of ATP. It is concluded that SPM Ca2+-ATPase may have a functional role in removal of cytosol Ca2+.