Complete sequence analysis of a gene (OS-9) ubiquitously expressed in human tissues and amplified in sarcomas

Amplification and overexpression of genes involved in cellular growth control occur frequently in human tumors. Using a chromosome microdissection‐based hybrid‐selection strategy, we recently identified two novel genes (OS‐9 and OS‐4) within 12q13–15, a region frequently amplified in human cancers. We now report further characterization of the full‐length OS‐9 cDNA sequence. This cDNA sequence consists of 2785 bp from which an open reading frame (ORF) with 667 amino‐acid residues was deduced. The predicted polypeptide was water soluble and acidic. We also demonstrate that the OS‐9 gene encoded a 2.8‐kb mRNA transcribed in all 16 human tissues examined, suggesting that OS‐9 is ubiquitously expressed in human tissues. OS‐9 was co‐amplified with CDK4 in three of five sarcoma tissues. Homology analysis of the amino‐acid sequence reveals significant similarities between OS‐9 and two ORFs deduced from genomic sequences in Caenorhabditis elegans and Saccharomyces cerevisiae. The region of similarity extended over 200 residues (approximately one‐third of each ORF), and eight cysteines were conserved in all three ORFs. These observations suggest that this region comprises a functional domain present in a novel evolutionarily conserved gene family defined by OS‐9.