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Literature summary for 3.6.1.5 extracted from

  • Madry, C.; Arancibia-Carcamo, I.L.; Kyrargyri, V.; Chan, V.T.T.; Hamilton, N.B.; Attwell, D.
    Effects of the ecto-ATPase apyrase on microglial ramification and surveillance reflect cell depolarization, not ATP depletion (2018), Proc. Natl. Acad. Sci. USA, 115, E1608-E1617 .
    View publication on PubMedView publication on EuropePMC

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
ADP + H2O Solanum tuberosum
-
AMP + phosphate
-
?
ATP + 2 H2O Solanum tuberosum overall reaction AMP + 2 phosphate
-
?
ATP + H2O Solanum tuberosum
-
ADP + phosphate
-
?

Organism

Organism UniProt Comment Textmining
Solanum tuberosum
-
-
-

Source Tissue

Source Tissue Comment Organism Textmining
commercial preparation
-
Solanum tuberosum
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
ADP + H2O
-
Solanum tuberosum AMP + phosphate
-
?
ATP + 2 H2O overall reaction Solanum tuberosum AMP + 2 phosphate
-
?
ATP + H2O
-
Solanum tuberosum ADP + phosphate
-
?

Synonyms

Synonyms Comment Organism
ecto-ATPase
-
Solanum tuberosum
NTPDase1/CD39
-
Solanum tuberosum

General Information

General Information Comment Organism
physiological function apyrase decreases microglial ramification and surveillance. Applying the ATPase apyrase, an enzyme which hydrolyzes ATP and ADP, reduces microglial process ramification and surveillance in acutely prepared postnatal day (P)12 rat hippocampal slices, suggesting that ambient ATP/ADP maintains microglial surveillance. But attempting to raise the level of ATP/ADP by blocking the endogenous ecto-ATPase (termed NTPDase1/CD39), which also hydrolyzes ATP/ADP, does not affect the cells' ramification or surveillance, nor their membrane currents, which respond to even small rises of extracellular [ATP] or [ADP] with the activation of K+ channels. This indicates a lack of detectable ambient ATP/ADP and ecto-ATPase activity, contradicting the results with apyrase. Contamination of commercially available apyrase by a high K+ concentration reduces ramification and surveillance by depolarizing microglia. Exposure to the same K+ concentration (without apyrase added) reduced ramification and surveillance as with apyrase. Dialysis of apyrase to remove K+ retains its ATP-hydrolyzing activity but abolishes the microglial depolarization and decrease of ramification produced by the undialyzed enzyme. Microglia are very sensitive to increases of extracellular ATP concentration, to which they respond by activating P2Y12 receptor-gated THIK-1 K+ channels, generating an outward K+ current which leads to a hyperpolarization of their membrane Solanum tuberosum