Putative false positive interactors in the DUALmembrane system

We have compiled a list of interactors that are repeatedly found in different screens with unrelated baits and which may represent typical false positives in the DUALmembrane system. Please keep in mind that this list is meant as a help when analyzing screening results. While it may identify non-specific interactors that turn up in some screens, we do not suggest that the proteins listed here are always false positives. If your interacting protein is found in the list below but you believe that its interaction with your bait may be biologically relevant, you should continue to confirm the interaction in an independent system, such as co-immuno- precipitation or in vitro binding experiments.

Interactor	Frequency	Comments
ATPases	Frequent	Mostly vacuolar ATPases, may be connected with sorting of particular bait proteins to the vacuoles of yeast.
Proteolipid proteins	Frequent
Ubiquitin	Frequent	Frequently isolated ifrom X-NubG libraries, less frequently from NubG-X libraries. Confirmed false positive, interacts with the Cub portion of the bait via the wild type ubiquitin. Isolated sequences often encode partially truncated ubiquitin, thereby creating a wild type Nub (N-terminal part of ubiquitin) fused to the NubG portion.
ADE2	Frequent	Frequently isolated when screening on SD-trp-leu-ade. Encodes the mammalian homologue of the yeast ade2 protein, capable of complementing the ade2 deficiency in the NMY32 and NMY51 reporter strains. Can be avoided by screening on SD-trp-leu-his-ade instead of SD-trp-leu-ade medium.
Translocon components	Rare	May interact with the bait upon translocation through the membrane due to spatial proximity. This is not a true false positive, as it reflects a biologically relevant interaction.
Signal peptidases	Rare	May reflect an interaction of the signal peptidase with type I baits upon cleavage of the signal sequence peptide.
Cytochrome C	Rare
Selenoprotein K	Rare

Last update: 12.6.2005