ABCG2, THE BREAST CANCER RESISTANCE PROTEIN (BCRP)

The ABCG2 half-transporter plays an important in normal physiology predominantly in protective roles at the maternal-fetal barrier and the blood-brain barrier and affects oral bioavailability of substrates. High expression in some cancers suggests it may also play a role in multidrug resistance in cancer. Polymorphic variants have been shown to impair trafficking of the protein to the cell surface, with the Q141K variant being associated with a higher incidence of gout. Loss of ABCG2 expression forms the genetic bases of the Jr(a-) blood type. This chapter will focus on more recent ABCG2 studies with particular focus on genetic variants and atomic structures. These more recent findings may lead to a better understanding of the function of ABCG2, potentially leading to the development of better inhibitors or to the development of compounds that are not substrates for the transporter.