We report the isolation and characterization of the growth arrest and DNA-damage-inducible gene, GADD153, from human cells and show that it is localized in the region 12q13.1-q13.2 on chromosome 12. Comparison of the human gene with the previously described hamster gene revealed a high level of conservation in both the structural and regulatory regions of the genes. Each is composed of four exons with intron/exon junctions maintained at the identical positions. The human Gadd153 protein shares 91% identity with the hamster protein in amino acid sequence, and 78% identity in nucleotide sequence. A 900-bp fragment of 5' flanking sequence from the human gene, when linked to the bacterial cat reporter gene, was found to exhibit promoter activity in HeLa cells which could be further activated by treatment with the DNA alkylating agent, methyl methanesulfonate. Sequence analysis indicated that the human promoter region is relatively G+C-rich and contains putative binding sites for multiple transcription factors, including recognition sites for TATA- and CAAT-binding proteins, six Sp1-binding sites, an activator protein-1 binding site, an E-26-specific sequence-binding protein-1 DNA-binding site, and four interleukin-6 response elements. Many of these sites are also present in an identical position in the hamster gene suggesting they may play an important role in regulating GADD153 expression.