Fig. 7.

Diverse sources of RDDGs promoters. Various scenarios that lead to the transcription of RDDG gene copies are illustrated. (A) Recruitment of proto-promoters from the CpG island-less region. (B) Recruitment of proto-promoters from the CpG-rich island. (C) Recruitment of a bidirectional (CpG-enriched) promoter from neighboring gene in the vicinity of the RDDG gene. (D) Recruitment of distant promoters in the genomic neighbourhood via the acquisition of a new 5'-untranslated exon–intron structure. (E) Sharing of the unidirectional (CpG-enriched) promoter from a neighboring gene in the vicinity of the RDDG gene. Exons and introns are represented by orange and gray (RDDG genes) or black (neighbouring genes in the case of bidirectional promoters) boxes and connecting lines. Distances between exons are not to scale.