text: Eukaryotic promoters are diverse and can be difficult to characterize, however, recent studies show that they are divided in more than 10 classes.
  Gene promoters are typically located upstream of the gene and can have regulatory elements several kilobases away from the transcriptional start site (enhancers). In eukaryotes, the transcriptional complex can cause the DNA to bend back on itself, which allows for placement of regulatory sequences far from the actual site of transcription. Eukaryotic RNA-polymerase-II-dependent promoters can contain a TATA box (consensus sequence TATAAA), which is recognized by the general transcription factor TATA-binding protein (TBP); and a B recognition element (BRE), which is recognized by the general transcription factor TFIIB. The TATA element and BRE typically are located close to the transcriptional start site (typically within 30 to 40 base pairs).
  Eukaryotic promoter regulatory sequences typically bind proteins called transcription factors that are involved in the formation of the transcriptional complex. An example is the E-box (sequence CACGTG), which binds transcription factors in the basic helix-loop-helix (bHLH) family (e.g. BMAL1-Clock, cMyc). Some promoters that are targeted by multiple transcription factors might achieve a hyperactive state, leading to increased transcriptional activity.
  * Core promoter – the minimal portion of the promoter required to properly initiate transcription
  ** Includes the transcription start site (TSS) and elements directly upstream
  ** A binding site for RNA polymerase
  *** RNA polymerase I: transcribes genes encoding 18S, 5.8S and 28S ribosomal RNAs
  *** RNA polymerase II: transcribes genes encoding messenger RNA and certain small nuclear RNAs and microRNA
  *** RNA polymerase III: transcribes genes encoding transfer RNA, 5s ribosomal RNAs and other small RNAs
  ** General transcription factor binding sites, e.g. TATA box, B recognition element.
  ** Many other elements/motifs may be present. There is no such thing as a set of "universal elements" found in every core promoter.
  * Proximal promoter – the proximal sequence upstream of the gene that tends to contain primary regulatory elements
  ** Approximately 250 base pairs upstream of the start site
  ** Specific transcription factor binding sites
  * Distal promoter – the distal sequence upstream of the gene that may contain additional regulatory elements, often with a weaker influence than the proximal promoter
  ** Anything further upstream (but not an enhancer or other regulatory region whose influence is positional/orientation independent)
  ** Specific transcription factor binding sites