Biology Reference
In-Depth Information
Fig. 17.1 A semi-logarithmic relation between the protein-protein interactome size (IS) and the
extent of noncoding regions of DNA in four species (Data from Stumpf et al. 2008 and Mattick
2004).
1
¼
Saccharomyces cerevisiae
;
2
¼
Drosophila melanogaster
;
3
¼
Caenorhabditis
elegans
;
4
¼
Homo sapiens
Or
e
14
:
3
ð
NTR
Þ
IS
¼
e
14
:
3
Þ
ð
NTR
Þ
¼ð
Þ
ð
NTR
Þ
10
6
¼ð
1
6
(17.4)
:
2. According to Eq.
17.4
, the interactome size of multicellular species is an
exponential function of their NTR's. Since NTR cannot be greater than 1, the
maximum size of the p-p interactomes in multicellular species is predicted to be
less than 1.6
10
6
. Since there are about 20,000 genes in the human genome,
The maximum number of the gene-gene interactions that can be encoded in the human
genome would be 1.6
10
6
/2
10
4
¼
80 per gene.
(17.5)
Statement 17.5 may be referred to as the Principle of the Maximum Interactome
Size of the human genome (PMISHG), or simply the Principle of the Maximum
Human Interactome (PMHI).
3. The deviation of
S. cerevisiae
from the straight line in Fig.
17.1
by a
¼
6 units
(or by a factor of e
6
¼
403) along the
y
-axis and b
¼
0.4 units (or 40%) along the
x
-axis may not be due to experimental errors but has a biological significance.
The anomaly here is that the budding yeast appears to have a much more complex
p-p interactome relative to the noncoding portions of its genome. The noncoding
potion of the yeast genome, that is, 0.3 or 30%, should be worth about e
4
55 edges
but its number estimated, based on empirical measurements (Stumpf et al. 2008),
is about 25,000 (see Table
17.3
). One possible rationale for this discrepancy can
