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Mg2+/Ca(2+)-ATPase activity is not enriched in synaptic vesicles isolated from rat cerebral cortex
G Rodríguez de Lores Arnaiz1, A Pellegrino de Iraldi
1Instituto de Biología Celular y Neurociencias Prof. Eduardo De Roberts Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Neurochemical Research
|March 1, 1997
Summary
Magnesium/Calcium-activated ATPases (Mg2+/Ca2+-ATPases) are present in synaptic vesicles. However, these enzymes are not preferentially concentrated in synaptic vesicles, making them unsuitable as specific markers for these neuronal organelles.
Area of Science:
- Neuroscience
- Biochemistry
- Cell Biology
Background:
- Neuronal ATPases are diverse enzymes with varied distribution in cellular membranes.
- Magnesium/Calcium-activated ATPases (Mg2+/Ca2+-ATPases) are known to be present in purified vesicle fractions.
Purpose of the Study:
- To investigate if Mg2+/Ca2+-ATPase activity is preferentially concentrated in synaptic vesicle fractions.
- To determine the suitability of Mg2+/Ca2+-ATPase as a marker for synaptic vesicles.
Main Methods:
- Rat cerebral cortex fractionation using differential centrifugation and sucrose gradient separation.
- Isolation of purified synaptic vesicle fractions.
- Assay of Mg2+/Ca2+-ATPase activities.
- Ultrastructural analysis of isolated fractions.
Main Results:
- Similar specific activities of Mg2+/Ca2+-ATPases were detected in all fractions containing synaptic vesicles and/or membranes.
- The study confirmed the presence of Mg2+ and Ca2+-ATPase activities within synaptic vesicle preparations.
Conclusions:
- Mg2+/Ca2+-ATPase activity is not exclusively or preferentially located in synaptic vesicles.
- The findings do not support the use of Mg2+/Ca2+-ATPase as a reliable marker for synaptic vesicles.