FIG. 1.

Schematic representation of four types of mouse claudin-18 transcripts and polypeptides. Organization of exons and introns and predictions of how the four types of transcripts are produced are shown. Solid boxes represent exons. The positions of the translation initiation and termination codons defining open reading frames are indicated. The alternatively inserted 12-bp sequence after exon 4 is depicted by an open box. Arrows indicate the positions of primers used for RT-PCR analysis (P1 to P5). Shaded boxes represent four transmembrane domains (TM1 to TM4). The nomenclature for the genes and their respective polypeptides is shown on the right for lung and stomach forms.