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Schematic diagram showing the transcription control regions in a hypothetical mRNA-producing, eukaryotic gene transcribed by RNA polymerase II. Such
a gene can be divided into its coding and regulatory regions, as defined by the transcription start site (arrow; +1). The coding region contains the DNA
sequence that is transcribed into mRNA, which is ultimately translated into protein. The regulatory region consists of 2 classes of elements. One class is
responsible for ensuring basal expression. The “promoter,” is often composed of the TATA box and/or INR and/or DPE elements direct RNA polymerase II
to the correct site (fidelity). However, in certain genes that lack TATA, the so-called TATA-less promoters, an initiator (INR) and/or DPE elements may
direct the polymerase to this site. Another component, the upstream elements, specifies the frequency of initiation; such elements can either be proximal
Source: Transcription: RNA Synthesis, Processing, and Regulation, Integrative Medical Biochemistry Examination and Board Review
(50–200 bp) or distal (1000–105 bp) to the promoter as shown. Among the best studied of the proximal elements is the CAAT box, but several other
Citation:
King
MW. Integrative
Medical
Examination
and Board
Review;
2014
Available
at: http://mhmedical.com/
Accessed:
May
elements (bound
by the
transactivator
proteins
Sp1,Biochemistry
NF1, AP1, etc)
may be used
in various
genes.
The
distal elements
enhance or repress
expression,
06,
2017
several of which mediate the response to various signals, including hormones, heat shock, heavy metals, and chemicals. Tissue-specific expression also
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Education.
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involves specific
sequences
this sort. The
orientation
of all the elements is indicated by the arrows within the boxes. For example, the
proximal promoter elements (TATA box, INR, DPE) must be in the 5′–3′ orientation, while the proximal upstream elements often work best in the 5′–3′