The Ly-6 family of cell surface molecules includes many members that have been characterized in the mouse. Until recently, very few Ly-6 family members had been described in the human. A significant development with important implications for novel gene discovery has been the growth of the public Expressed Sequence Tag (EST) database. Here we report that, through the application of bioinformatics analysis to the dbEST database, we obtained the sequence of human TSA-1/SCA-2, a new member of the human Ly-6 family. In addition, we identified full-length clones encoding this molecule as well as expression data in various tissues. Sequencing of the clones identified this way confirmed the sequence predicted through bioinformatics. This study constitutes an example of the application of bioinformatics to the analysis of the recently expanded databases for the identification of genes of potential importance in the immune system.