Promoter proximal elements are gene expression regulatory elements found around 200 nucleotides before the transcriptional start site, allowing the binding of transcription factors.
There can be multiple promoter proximal elements regulating the expression of the same gene or regulon. This allows different transcription factors to influence expression levels.
Distal enhancers have a similar effect as promoter proximal elements, however due to their distance from the TSS, their impact is limited. Therefore, distal enhancers have a weaker effect.