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. Author manuscript; available in PMC: 2015 May 1.
Published in final edited form as: Chem Phys Lipids. 2014 Jan 10;0:23–43. doi: 10.1016/j.chemphyslip.2013.12.013

Figure 3. Model for the regulation of UASINO-containing genes by changing PA levels.

Figure 3

In cells grown in the absence of inositol, PI levels are low due to the limited availability of endogenously produced inositol, which leads to the accumulation of PA. Under these growth conditions, the Opi1p transcriptional repressor localizes to the cytoplasmic face of the ER though dual interactions with PA and Scs2p, and the transcription of UASINO-containing genes, regulated by the Ino2p-Ino4p complex, are maximally derepressed. Upon the addition of inositol, PI synthesis dramatically increases, which causes the rapid consumption of the ER pool of PA. This drop in PA levels releases Opi1p, which translocates to the nucleus, where it binds to Ino2p and represses the transcription of UASINO-containing genes, which is mediated by the general transcriptional repressor Sin3p.