Strategies for Y2H screening.

There are three main strategies for large-scale Y2H screens, briefly: i) matrix – all bait-prey pairs are tested, ii) library – preys are pooled and growing colonies are picked and then sequenced, and iii) two-phase pooling – preys are pooled in a first phase and in a second phase baits that reported interactions are pooled and screened against individual preys (see [69], [87], [88] for reviews). In the Parrish screen pools group preys compared to for Stelzl. The screening completeness is the proportion of the whole interactome search space that was accessible to the screen: where is the number of ORFs cloned for baits, is the number of ORFs cloned for preys and is the estimated number of protein coding genes. In practice, the assay and sampling sensitivity of Y2H screens greatly diminish the effective completeness [73]. For that same reason, screening completeness should not be misconstrued with assay sensitivity – for which the average number of interaction partners is a better indicator.