Transcription of genes encoding pregnancy-specific glycoproteins is regulated by negative promoter-selective elements

containing thymidine kinase promoter. Detailed transcriptional and DNA‐protein analyses of the proximal repressor region (fi605 to fi254) revealed the presence of both negative and positive cis-acting elements. Disruption of the repressive functions resulted in an enhanced transcription of the reporter constructs. In conclusion, these results demonstrate that PSG-5 gene transcription is highly repressed by promoter-selective negative regulatory regions and the relief of repression allows enhanced PSG-5 gene transcription irrespective of the cell type. Furthermore, our findings suggest that PSG genes are expressed mainly through a derepression mechanism.