In Ensembl sequence similarity searches, HPID stores protein interactions on the basis of Ensembl human peptide IDs. The user obtains an Ensembl human peptide ID via the BLAST service of Ensembl. It is thus possible to locate predicted interactions stored in HPID by means of the user¡¯s Ensembl human peptide ID. The results are stored in a local database that the user creates. The user submits his or her Ensembl human peptide ID and can examine the experimental data and the potential interaction data.