Mercury (Hg2+) and methylmercury (CH3Hg2+) bind to sulfhydryl groups including thiol-containing molecules such as glutathione (GSH), cysteine (Cys), homocysteine (Hcy), and N-acetylcysteine (NAC). These conjugated mercury species are taken up basolaterally by organic anion transporters (OAT) and apically by amino acid transporters including L -cysteine, system B0,+, and Na+-dependent low-affinity L -systems. Efflux transporters on the brush border membrane include multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP).