Fig. 8. Model. (A) Ap activity regulation under wild-type conditions. Once dLMO is expressed, Ap detaches from Chip and is degraded. Transcriptional activation of its target genes is abolished. For simplicity we depict degradation of Ap monomer. It is also possible that any form of incomplete Ap;Chip complex is degraded. (B) Inhibition of Ap:Chip tetramer formation by ChipLID. (C) ChAp binds to Ap target sites on DNA and displaces endogenous Ap. dLMO cannot interfere. Ap is degraded. (D) Inhibition of Ap activity by dLMO can be reverted by providing the fusion protein dLAp. dLAp competes with dLMO and activates Ap-dependent transcription.