Hi! I want to build a PPI network by union of three PPI databases. How should I do that, Is there an online tool to do so? If yes then which one and how to do the above stated task. Thank you in advance. Please help me.
You could use iRefIndex. It integrates data from several protein-protein interaction databases. The last update was two years ago though. If you need to do it yourself, you need to map all interaction partners to the same reference gene or protein set. I typically map all interaction partners to EnsEMBL genes because I usually need gene level interactions and also this is easier than trying to identify protein isoforms across databases. If the latter is what you want, look at the method in the iRefIndex paper.