The genomic DNA for ENA-78 has been obtained from a human chromosome 4 flow-sorted cosmid library. Three out of 25,000 screened single colonies yielded the same 2.2-kB EcoRI ENA-78 gene fragment. A similar size fragment was observed on genomic southern blots, suggesting the presence of a single ENA-78 gene. The transcriptional start site was localized using a 5' RACE protocol on first strand cDNA prepared from stimulated alveolar type-II epithelial cell (A549) poly(A) mRNA. The ENA-78 gene contains four exons and three introns and the open reading frame of 342 nucleotides encodes for a protein of total 114 amino acids. The 5' flanking region contains potential binding sites for several nuclear factors such as AP-2, NF-kappa B, and interferon regulatory factor-1.