FIGURE 9.

Model for Sumo-mediated recruitment of INO1 to the NPC. Shown is model for the proposed role of sumoylation in the NPC targeting and transcriptional activation of the INO1 gene. (A) In a repressed state, INO1 is positioned in the nucleoplasm. (B) Reducing levels of inositol in the medium leads to recruitment of Siz2 to the INO1 locus and increased Siz2-mediated sumoylation of INO1-associated proteins. These events are required for the targeting of the INO1 locus to the NPC where it interacts with NPC-associated Ulp1. Ulp1 supports the association of INO1 with the NPC and functions to desumoylation of INO1 bound proteins in regions containing the GRS1 and the ORF. Desumoylation of INO1-associated proteins is proposed to promote INO1 transcription.