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

The rabbit polyclonal antibody against rat organic anion transporting polypeptide 2 (oatp2) was raised and immunoaffinity-purified. Western blot analysis for oatp2 detected two bands (similar to 74 and 76 kDa) in rat brain and a single band (76 kDa) in the liver. By immunohistochemical analysis, the oatp2 immunoreactivity was specifically high at the basolateral membrane of 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, as well as the substrates previously reported. These data reveal the exact distribution of the rat oatp2 at the protein level in the liver, and that oatp2 appears to be involved in the multispecificity of the uptaking substrates in the liver and brain. (C) 1999 Federation of European Biochemical Societies.