FIGURE 1.

Purification and ATPase activity of ABCA1, ABCA7, and ABCA4. Wild type (WT) and mutant ABCA1, ABCA4, and ABCA7 in which lysine residues in the Walker A motifs of NBD1 and NBD2 were replaced with methionine (ABCA-MM) all containing a 9-amino acid C-terminal epitope were expressed in HEK293T cells and purified on a Rho1D4 immunoaffinity matrix. A, Coomassie Blue-stained gel and Rho1D4-labeled Western blot of the ABCA1 and ABCA7 detergent-solubilized cell lysate (lane labeled I) and purified protein eluted from the immunoaffinity column with the 1D4 peptide (lane labeled E). The arrow identifies the position of the ABCA1 and ABCA7 transporters. B, ATPase activity of WT and mutant ABCA proteins. Immunoaffinity purified WT ABCA1, ABCA7, and ABCA4 and their MM mutants were reconstituted into brain polar lipid for analysis of their ATPase activity. Results are the mean ± S.D. for three independent experiments.