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Published on: May 25, 2011
Calcium-stimulated adenosine triphosphatases in synaptic membranes
Journal of Neurochemistry
|December 1, 1981
Summary
Researchers studied ATPases in rat brain synapses, identifying a calcium-dependent ATPase potentially involved in calcium transport. This enzyme, enhanced by calmodulin, shows specific inhibition by agents like vanadate.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Synaptic membranes contain various ATPases crucial for neuronal function.
- Understanding these enzymes is key to elucidating neurotransmission and calcium homeostasis.
Purpose of the Study:
- To characterize ATPases in rat cerebral cortex synaptic membranes.
- To identify potential calcium-transporting ATPases within these preparations.
Main Methods:
- Enzyme activity assays on synaptic membrane preparations.
- Investigated Mg2+-ATPase, Ca2+-dependent ATPases, and calmodulin-stimulated activity.
- Utilized specific inhibitors like vanadate and La3+ for characterization.
Main Results:
- Identified intrinsic (Na+ + K+)-ATPase and contaminating Mg2+-ATPase.
- Characterized a Mg2+-ATPase, a high-concentration Ca2+-dependent ATPase, and a high-affinity (Ca2+ + Mg2+)-ATPase.
- The (Ca2+ + Mg2+)-ATPase activity was significantly enhanced by calmodulin.
- Specific inhibitors like vanadate and La3+ selectively inhibited the (Ca2+ + Mg2+)-ATPase.
Conclusions:
- The characterized (Ca2+ + Mg2+)-ATPase, particularly its calmodulin-stimulated form, exhibits properties consistent with a role in neuronal calcium transport.
- This enzyme may be critical for regulating intracellular calcium levels in nerve endings.
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