I need to programmatically access human protein-protein interactions to retrieve interactions between specific classes of molecules, but there are many protein-protein interactions databases around, especially for Homo sapiens (e.g. BIOGrid, HPRD, Reactome, MINT, DIP, STRING... just to name a few).
What's the most comprehensive resource altogether? Is there a database that somehow integrates all of the other ones? I'd just need a flat text file with all the interactions and the classes of the interacting molecules (e.g. 'transcription factor', 'GTPase', 'lipid phosphatase'...).