Functional analysis of ABCA8, a new drug transporter

Biochem Biophys Res Commun. 2002 Oct 18;298(1):41-5. doi: 10.1016/s0006-291x(02)02389-6.


We examined the transport capacity in Xenopus laevis oocytes of human EST KIAA0822/ABCA8, a member of the ABC superfamily. Substrates of ABCC2/MRP-2 such as [14C]estradiol-beta-glucuronide, taurocholate, and LTC4, and of organic anion transporter (OAT), such as para-aminohippuric acid, ochratoxin-A, were significantly accumulated while tetraethylammonium and doxorubicin were not. The transport of [14C]estradiol-beta-glucuronide was ATP-dependent and K(m) and V(max) values of 30.4microM and 66.9pmol/h/egg, respectively, were estimated. The transport of [14C]estradiol-beta-glucuronide was inhibited by substrates/inhibitors of ABCC2/MRP-2, but not by those of the organic cation transporter and multidrug resistance protein (MDR)-1. KIAA0822/ABCA8 possesses two ATP-binding sites and fourteen transmembrane domains. Northern blot analysis revealed expression in most organs, especially in heart, skeletal muscle, and liver. Thus, ABCA8 is a new member of the xenobiotic transporter ABC-subfamily.

MeSH terms

  • ATP-Binding Cassette Transporters / antagonists & inhibitors
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / physiology*
  • Animals
  • Biological Transport / drug effects
  • Cells, Cultured
  • Estradiol / analogs & derivatives*
  • Estradiol / metabolism
  • Humans
  • Kinetics
  • Multidrug Resistance-Associated Protein 2
  • Oocytes / metabolism
  • RNA, Messenger / biosynthesis
  • Substrate Specificity
  • Tissue Distribution
  • Xenobiotics / pharmacology
  • Xenopus Proteins / genetics
  • Xenopus Proteins / physiology*
  • Xenopus laevis


  • ABCA8 protein, Xenopus
  • ABCC2 protein, human
  • ATP-Binding Cassette Transporters
  • Multidrug Resistance-Associated Protein 2
  • RNA, Messenger
  • Xenobiotics
  • Xenopus Proteins
  • estradiol-17 beta-glucuronide
  • Estradiol