Skip to main content
. 2007 Feb 6;104(7):2307–2312. doi: 10.1073/pnas.0607153104

Fig. 4.

Fig. 4.

Examples of environment-specific synthetic genetic interactions. (A) Alternative routes to phosphatidylcholine biosynthesis in yeast. Cho2p, phosphatidylethanolamine methyltransferase; Opi3p, phospholipid methyltransferase; Cki1p, choline kinase; Pct1p, cholinephosphate cytidylyltransferase; Cpt1p, sn-1,2-diacylglycerol cholinephosphotransferase; PS, phosphatidylserine; PE, phosphatidylethanolamine; PME, phosphatidyl-N-methylethanolamine; PDME, phosphatidyl-N-dimethylethanolamine; CHO, choline; PCHO, choline phosphate; CDPCHO, CDP-choline; PC, phosphatidylcholine. (B) One member of the SSL pair makes an important individual contribution to growth under a different condition. CHO2 and PCT1 can compensate null mutations in one another under nutrient-rich (YPD) conditions, but the cho2Δ mutant is slow growing on minimal medium. (C) The double deletant becomes viable under a different condition. The SAM1/SAM2 duplicate gene pair, which encodes two distinct forms of S-adenosylmethionine (AdoMet) synthetase, can compensate null mutations in one another, and the double mutants are inviable under nutrient-rich (YPD) conditions. However, addition of AdoMet to the medium yields viable double mutants.