9780521516358book.pdf

of other transcription factors also bind sequentially to form an initiation complex that

includes RNA polymerase, subsequent to which transcription is initiated. In addition

to the TATA box, aCAT box(consensus GGCCAATCT) is often located at about

80 bp, which is an important determinant of promoter efficiency. Manyupstream

promoter elements(UPEs) have been described that are either general in their action

or tissue (or gene) specific. GC elements that contain the sequence GGGCG may be

present at multiple sites and in either orientation and are often associated with

housekeeping genessuch as those encoding enzymes involved in general metabolism.

Some promoter sequence elements, such as the TATA box, are common to most genes,

while others may be specific to particular genes or classes of genes.

Of particular interest is a class of promoter first investigated in the virus SV40

and termed an enhancer. These sequences are distinguished from other promoter

sequences by their unique ability to function over several kilobases either upstream

(a)

Promoters

–35

TTGACA

–10

TATA

+1 Structural

gene

(b)

Upstream promoter elements

Variable

distance

enhancer

–80

CAAT or

G+C-rich

–35

TATA

+1 Structural

gene

3 

(c)

TFII D

TFII A

TFII B

TFII E/F

RNA

pol II

–80

CAAT or

G+C-rich

–35

TATA

+1 Structural

gene

3 

5 

5 

3 

5 

Fig. 5.15(a) Typical promoter elements found in a prokaryotic cell (e.g.E. coli). (b) Typical promoter

elements found in eukaryotic cells. (c) Generalised scheme of binding of transcription factors to the promoter

regions of eukaryotic cells. Following the binding of the transcription factors IID, IIA, IIB, IIE and IIF a

pre-initiation complex is formed. RNA polymerase II then binds to this complex and begins transcription

from the start pointþ1.

156 Molecular biology, bioinformatics and basic techniques