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. 2016 Jun 6;7:869. doi: 10.3389/fmicb.2016.00869

FIGURE 2.

FIGURE 2

Schematic representation of typical immediate-early, early and late gene promoters. These examples come from EBV and HSV-1. pBZLF1 is the promoter of the EBV immediate-early gene encoding the viral transcription factor called EB1, BZLF1, or Zta. pICP4 is the promoter of the HSV-1 immediate-early gene encoding the viral transcription factor called ICP4. The negative cis-regulatory elements are indicated in red. The positive cis-regulatory elements are labeled in green. pBHRF1 is the promoter of the EBV early gene encoding the BHRF1 protein. EB1 and R are the viral transcription factors responsible for the activation of early gene expression. pTK is the promoter of the HSV-1 early gene encoding the Thymidine Kinase protein. pBcLF1 is the promoter of the EBV late BcLF1 gene that encodes the major capsid protein. pgC is the promoter of the HSV-1 late gene encoding the glycoprotein C. The viral late promoters do not contain any positive or negative cis-regulatory elements. In addition to the TATA box element, HSV-1 late promoters contain an initiator element (inr). By contrast to HSV-1, EBV late promoters contain a TATT box at the place of the canonical TATA box. IE, immediate early; E, early; L, late.