Biology Reference
In-Depth Information
ATG
-600
-500
-400
-300
-200
-100
610
Human
610
Chimpanzee
610
Gorilla
449
Pig
432
Bull
328
Sheep
347
Gazelle
GATA1
OCT1
cMYB
SP1
NF1
AP1
BARBIE
SRY
vMYB
GFI1
427
Mouse
427
Rat
427
Guinea pig
Figure 5.1.
Comparison of the promoter sequences from the
SRY
genes of ten mammals
(redrawn from Margarit
et al
., 1998). Putative transcription factor binding sites are
denoted by boxes above or below the sequence indicating their position on the sense or
antisense strands respectively. Solid circles indicate gap positions present in the sheep
and gazelle sequences as compared with the bull sequence. GATA; CMYB; NF1;
BARBIE; vMYB; OCT1; SP1; AP1; SRY; GFI1.
differences in expression. Sorci-Thomas and Kearns (1995) identified seven sites
within the proximal promoter region of the
APOA1
gene which differed between
human and African green monkey. These authors then tested the functional sig-
nificance of these sequence changes by mutating the human promoter to the
simian sequence and testing promoter strength by reporter gene expression assay.
Substitutions at three of the sites (
48 relative to the transcrip-
tional initiation site) were found individually to increase the activity of the wild-
type human promoter to ~60-65% of that of the African green monkey. In
addition, two double mutations (
189,
144 and
144) restored promoter
activity to the same level as found in the monkey. Thus, we may therefore infer
that several substitutions in the
APOA1
gene must have occurred during primate
evolution which together served to determine the specific level of
APOA1
gene
transcription in the different species.
Even if promoter elements are conserved, their relative location may not be.
Thus the presence of four perhaps five DNase I hypersensitive sites in the
144/
48 and
189/
-globin
