A polarized localization of amino acid/carnitine transporter B(0,+) (ATB(0,+)) in the blood-brain barrier

Biochem Biophys Res Commun. 2008 Nov 14;376(2):267-70. doi: 10.1016/j.bbrc.2008.08.122. Epub 2008 Sep 2.


Brain capillary endothelial cells control the uptake and efflux from the brain of many hydrophilic compounds due to highly specialized transporters often localized in a polarized way. Localization of Na(+)- and Cl(-)-dependent amino acid and carnitine transporter B(0,+) (ATB(0,+)) was studied in a co-culture of bovine brain capillary endothelial cells (BBCEC) grown on filters above astrocytes (an in vitro blood-brain barrier model). Immunoblotting and three-dimensional immunocytochemistry analysis with anti-B(0,+)antibodies demonstrated the presence of this transporter and its prevalent co-localization with P-glycoprotein i.e. at the apical side. The sensitivity of leucine uptake through the apical membrane to 2-aminobicyclo-[2.2.1]-heptane-2-carboxylic acid (BCH), D-serine as well as sodium and chloride replacement confirm the functioning of ATB(0,+) and suggests an important physiological role of ATB(0,+) in controlling the delivery of amino acids and carnitine to the brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport System ASC / metabolism*
  • Amino Acid Transport Systems, Neutral / metabolism*
  • Amino Acids, Cyclic / pharmacology
  • Animals
  • Blood-Brain Barrier / drug effects
  • Blood-Brain Barrier / metabolism*
  • Carnitine / metabolism
  • Cattle
  • Leucine / metabolism
  • Rats


  • Amino Acid Transport System ASC
  • Amino Acid Transport Systems, Neutral
  • Amino Acids, Cyclic
  • 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid
  • Leucine
  • Carnitine