“…Because the assumption is that interactions that are present multiple times are more reliable (given higher weight) a bias is introduced due to over-representation by popular methods for PPI identification, such as the yeast two-hybrid system (Y2H) [ 11 , 12 ] and affinity capture-mass spectrometry (affinity capture-MS) [ 13 , 14 ]. The Y2H method requires that the two proteins localize to the nucleus; however, integral membrane proteins expressed in an aqueous nuclear environment may aggregate or misfold [ 11 , 12 , 15 ], resulting in depletion of these proteins from the final interaction dataset. Also, the datasets derived from affinity capture-MS can be biased against integral membrane proteins, because biochemical purifications require detergents to isolate proteins away from the lipid bilayer [ 16 ].…”