Schematic representation of the genes and mRNAs for the human HCC-1 (A) and HCC-2 (B), and the HCC-2/HCC-1 gene complex (C). The open and filled boxes represent coding and untranslated regions, respectively. Hatched boxes correspond to the nontranslated regions for monocistronic messages of the tandem gene. The sizes (bp) of exons (E) and introns (I), start (AUG) and stop (UGA or UAA) codons, the numbers of amino acids (aa), and the expressed sequence tag (EST) clones (R99672, R16807, H62013) are indicated. Promoters (P) are marked by arrows. The entire gene complex consists of six SstI restriction fragments (16 kbp, 2.2 kbp, 1.813 kbp, 0.542 kbp, 196 bp, and 16 bp). TATA-box motifs are located upstream of the transcription start in both genes. Exon E δ′ and E 1′ are only present in the monocistronic cDNAs.