Mn2+-stimulated ATPase in rat brain.

Divalent cation ATPases were prepared from rat brain synaptic vesicles, synaptosomal plasma membranes, and plasma membranes from the brain stem and sciatic nerve and tested for optimal stimulation by Mn2+, Mg2+, or Ca2+. ATPase in the synaptic vesicle subfraction was optimally stimulated by Mn2+. All plasma membrane preparations were optimally stimulated by Mg2+. Separate Mn2+ and Mg2+ ATPases could not be distinguished by either chemical inactivation or substrate preference criteria. Mn2+ stimulated ATPase in the micromolar range and it is suggested that Mn2+ interaction with ATPase may be of physiological and/or toxicological importance by being related to the cellular metabolism of this element.