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Schematic 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, typically after extensive mRNA processing via splicing (Figures 36–12, 36–13,
36–14, 36–15, and 36–16. The regulatory region consists of two classes of elements. One is responsible for ensuring basal expression. The “promoter,” is
often composed of the TATA box and/or Inr and/or DPE elements (see Table 36–3), directs RNA polymerase II to the correct site (fidelity). However, in
certain genes that lack a consensus TATA, the so-called TATA-less promoters, an initiator (Inr) and/or DPE elements may direct the polymerase to this
Source: Structure, Function, & Replication of Informational Macromolecules, Harper's Illustrated Biochemistry, 30e
site. Another component, the upstream elements, specifies the frequency of initiation; such elements can either be proximal (50–200 bp) or distal (1000–
Citation:
Rodwell
VW, Bender
DA,the
Botham
KM, Kennelly
Weil P.elements
Harper's Illustrated
Biochemistry,
30e; 2015
Available
at: (bound by the
105 bp) to the
promoter
as shown.
Among
best studied
of thePJ,
proximal
is the CAAT
box, but several
other
elements
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transactivator proteins Sp1, NF1, AP1, etc; Table 36–3) may be used in various genes. The distal elements enhance or repress expression, several of
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which mediate
the response
various signals,
including
hormones,
heat shock, heavy metals, and chemicals. Tissue-specific expression also involves
specific sequences of this sort. The orientation dependence of all the elements is indicated by the arrows within the boxes. For example, the proximal