Conserved Walker A cysteines 431 and 1074 in human P-glycoprotein are accessible to thiol-specific agents in the apo and ADP-vanadate trapped conformations.

ABSTRACT: P-Glycoprotein (P-gp) is an ATP-binding cassette efflux transporter involved in the development of multidrug resistance in cancer cells. Although the mechanism of P-gp efflux has been extensively studied, aspects of its catalytic and transport cycle are still unclear. In this study, we used conserved C431 and C1074 in the Walker A motif of nucleotide-binding domains (NBDs) as reporter sites to interrogate the interaction between the two NBDs during the catalytic cycle. Disulfide cross-linking of the C431 and C1074 residues in a Cys-less background can be observed in the presence of M14M and M17M cross-linkers, which have spacer arm lengths of 20 and 25 Å, respectively. However, cross-linking with both cross-linkers was prevented in the ADP-vanadate trapped (closed) conformation. Both C431

SUBMITTER: Sim HM 

PROVIDER: S-EPMC3850068 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature