CLONING AND FUNCTIONAL CHARACTERIZATION OF A POTENTIAL-SENSITIVE, POLYSPECIFIC ORGANIC CATION TRANSPORTER (OCT3) MOST ABUNDANTLY EXPRESSED IN PLACENTA

摘要: We have isolated a cDNA from rat placenta which, when expressed heterologously, mediates the transport of wide spectrum organic cations. The codes for protein 551 amino acids containing 12 putative transmembrane domains. Northern blot analysis indicates that this transporter is most abundantly in and moderately intestine, heart, brain. expression comparatively low kidney lung undetectable liver. This distinct previously cloned cation transporters (OCT1, OCT2, NKT, NLT, RST, OCTN1). When HeLa cells, induces tetraethylammonium guanidine. Competition experiments indicate process recognizes large number cations, including neurotoxin 1-methyl-4-phenylpyridinium, as substrates. cDNA-induced markedly influenced by extracellular pH. However, Xenopus laevis oocytes, electrogenic, associated with transfer positive charge into oocytes. Under voltage clamp conditions, evokes inward currents are concentration- potential-dependent. potential-sensitive transporter, designated OCT3, represents new member OCT gene family.