In this study, we report the cloning of porcine UPII genomic DNA, which contains a putative full-length open reading frame encoding the UPII protein. A comparison of the porcine UPII gene coding sequence with the previously published mouse UPII sequence demonstrates that the exon sequences are only partially conserved. Northern and immunohistochemical analyses show that the porcine UPII gone is expressed only in the urothelium and that the protein specifically localizes to urothelial superficial cells. Among urothelial superficial cells, 8.5-9.8% of umbrella cells expresses the UPII gene. A 2-kb region of the porcine UPII promoter contains multiple transcription factor binding sites, including GC-boxes, SP1, AP2, and GATA-box sites, but no TATA or CAAT-box sequences. A sequence comparison of the porcine and murine UPII promoter genes by the MEME system allowed two conserved motifs to be identified. suggesting that these sequences have cis-acting regulatory roles. Sequence homologies between the motifs A and B of the two species are 79% and 80%, respectively, although their relative locations are different. Our results show that the porcine UPII gene is expressed highly and specifically in the bladder urothelium. (C) 2002 Elsevier Science (USA). All rights reserved.