... E552 in NBD1 and E1197 in NBD2. Tofurther characterize the role of these residues in catalysis, we created in Abcb1a the single-site mutants E552D, N and A in NBD1, and E1197D,N and A in NBD2, ... further the role of the IC in the catalysis of ABC transporters, we created, in Abcb1a, six single-site mutants (E552D, N and A, and E1197D, N and A,) and three double-mutants(E552Q ⁄ E1197Q, E552Q ... created the following novelmutants: E552N, E1197N, E552Q ⁄ K1072R and K429R ⁄ E1197Q, to further characterize the role of the IC residues in the catalytic mechanism of Abcb1a. Asseen in Fig....