TY - JOUR T1 - Characterization of the ATPase Activity of Human ATP-binding Cassette Transporter-2 (ABCA2) JF - In Vivo JO - In Vivo SP - 657 LP - 660 VL - 19 IS - 4 AU - VLADIMIR BELJANSKI AU - ATHENA SOULIKA AU - JODY M. TUCKER AU - DANYELLE M. TOWNSEND AU - WARREN DAVIS, JR. AU - KENNETH D. TEW Y1 - 2005/07/01 UR - http://iv.iiarjournals.org/content/19/4/657.abstract N2 - 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-β-cyclodextrin. However, competitive binding of a pseudo-substrate, 8-azido-[α-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. Copyright © 2005 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved ER -