The AAT web server at Michigan Tech identifies genes in a DNA sequence by comparing the query sequence against cDNA and protein sequence databases:
  Human_Gene_Index, a database of human cDNA sequences at TIGR,
  dbEST, a database of EST sequences at NCBI,
  SwissProt, a database of protein sequences at University of Geneva,
  nr, a database of non-redundant protein sequences at NCBI.

The AAT web server also predicts genes and combines database matches with prediction results. Note that the prediction might not work well for non-human sequences because the sequence statistics was collected from human DNA sequences.