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Ontogenetic profile of ecto-5'-nucleotidase in rat brain synaptic plasma membranes.

Authors: Stanojevic, I  Bjelobaba, I  Nedeljkovic, N  Drakulic, D  Petrovic, S  Stojiljkovic, M  Horvat, A 
Citation: Stanojevic I, etal., Int J Dev Neurosci. 2011 Jun;29(4):397-403. Epub 2011 Mar 23.
Pubmed: (View Article at PubMed) PMID:21414400
DOI: Full-text: DOI:10.1016/j.ijdevneu.2011.03.003

Ecto-5'-nucleotidase (CD73; EC 3.1.3.5, e-5NT) is regarded as the key enzyme in the extracellular formation of adenosine, which acts as a neuromodulator and important trophic and homeostatic factor in the brain. In the present study, we have investigated e-5NT activity, kinetic properties concerning AMP hydrolysis and the enzyme protein abundance in the purified synaptic plasma membrane (SPM) preparations isolated from whole female rat brain at different ages. We observed pronounced increase in AMP hydrolyzing activity in SPM during maturation, with greatest increment between juvenile (15-day-old) and pre-pubertal (30-day-old) rats. Immunodetection of e-5NT protein in the SPM displayed the reverse pattern of expression, with the maximum relative abundance at juvenile and minimum relative abundance in the adult stage. Negative correlation between the enzyme activity and the enzyme protein abundance in the SPM indicates that e-5NT has additional roles in the synaptic compartment during postnatal brain development, other than those related to AMP hydrolysis. Determination of kinetic parameters, K(m) and V(max), suggested that the increase in the enzyme activity with maturation was entirely due to the increase in the enzyme catalytic efficiency (V(max)/K(m)). Finally, double immunofluorescence staining against e-5NT and presynaptic membrane marker syntaxin provided first direct evidence for the existence of this ecto-enzyme in the presynaptic compartment. The results of the study suggest that e-5NT may be a part of general scheme of brain development and synapse maturation and provide rationale for the previously reported inconsistencies between enzyme immunohistochemical and biochemical studies concerning localization of e-5NT in the brain.

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RGD Object Information
RGD ID: 5134346
Created: 2011-06-29
Species: All species
Last Modified: 2011-06-29
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.