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Beljanski V , Soulika A , Tucker JM , Townsend DM , Davis Jr W , Tew KD
Characterization of the ATPase activity of human ATP-binding cassette transporter-2 (ABCA2)
In Vivo. 2005 ;19(4) :657-660
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Background: ABCA2 is a member of the ATP binding cassette transporter family with functional roles in cholesterol homeostasis and drug resistance. Materials and methods: In order to characterize its ATPase activity, we transfected HEK293 cells with an ABCA2 mammalian expression system and isolated ABCA2-enriched membranes. Results: We found no measurable ATPase activity of ABCA2 in isolated membranes, except in the presence of the methyl-?-cyclodextrin. However, competitive binding of a pseudo-substrate, 8-azido-[?-32P]-ATP, was demonstrated. CHO cells transfected with ABCA2 did not have a higher rate of endogenous ATP hydrolysis when compared to the mock-transfected cells. Conclusion: Overall, we conclude that, while ABCA2 may have low levels of ATPase activity that can be substrate-stimulated, it is more likely to have a regulatory role in cell physiology.
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