Immunohistochemical distribution and functional characterization of an organic anion transporting polypeptide 2 (oatp2)

The rabbit polyclonal antibody against rat organic anion transporting polyp eptide 2 (oatp2) was raised and immunoaffinity-purified. Western blot analy sis for oatp2 detected two bands (similar to 74 and 76 kDa) in rat brain an d a single band (76 kDa) in the liver. By immunohistochemical analysis, the oatp2 immunoreactivity was specifically high at the basolateral membrane o f rat hepatocytes. Functionally, the oatp2-expressing oocytes were found to transport dehydroepiandrosterone sulfate, delta(1) opioid receptor agonist [D-Pen(2),D-Pen(5)]enkephalin, Leu-enkephatin, and biotin significantly, a s well as the substrates previously reported. These data reveal the exact d istribution of the rat oatp2 at the protein level in the liver, and that oa tp2 appears to be involved in the multispecificity of the uptaking substrat es in the liver and brain. (C) 1999 Federation of European Biochemical Soci eties.