The full-length coding sequence of mouse organic anion-transporting polypeptide (designated mouse Oatp-5) has been cloned from mouse kidney cDNA library. Analysis of the 5'-untranslated region (5'-UTR) of Oatp-5 cDNA through capsite cloning reveals two possible transcription start sites that are 4-bp apart. The 3'-untranslated region (3'-UTR) of Oatp-5 cDNA contains an early polyadenylation signal, indicating the possibility that mRNAs with different 3'-UTR lengths may coexist. Deduced amino acid sequence of mouse Oatp-5 protein contains 670 amino acids and has 10 putative transmembrane domains, multiple potential glycosylation and phosphorylation sites. Tissue-specific expression studies indicate that mouse Oatp-5 is expressed only in kidney. Studies on the developmental expression reveal that there is no significant expression of Oatp-5 mRNA in mouse kidney for at least 3 weeks after birth, and adult levels of Oatp-5 mRNA expression are attained more than 6 weeks after birth. Phylogenetic analysis reveals that mouse Oatp-5 is an ortholog of rat Oatp-5.