Biomedical Engineering Reference
In-Depth Information
6
10
A
B
Front
Back
8
4
gradient reversed
6
gradient reversed
2
4
2
Front
Back
0
0
0
20
40
60
80
100
0
50
100
Time (s)
Time (s)
t=90 s
t=0 s
t=50 s
C
D
E
3.2
F
G
1
0.8
3.15
0.6
A
B
m
0.4
3.1
0.2
0
3.05
-5
-4
-3
-2
-1
0
1
2
3
4
5
-180
0
180
x (
μ
m)
Angle (degrees)
Figure 3.13.
A: The value of
A
as a function of time at the front of the cell
(black line) and the back of the cell (red line) as a response to a gradient reversal
experiment. B: The external concentration (
S
) before and after gradient reversal at
t=50 s. C-E: Value of
A
along the perimeter of the cell in a linear gray scale at
different times. F: Values of
A
and
B
m
, normalized by their maximum value, along
the perimeter at t=90 s. G: Value of
B
as a function of space measured along the
symmetry axis of the cell, parallel to the gradient (drawn as a red line in E). (See
color insert.)
would be coupled to the downstream modules responsible for Ras and PH-
domain protein localization. This specific realization of our model naturally
solves the problem of how to ensure the proper balance between activation and
inhibition in the system - it occurs naturally because these are both created
by G-protein disassociation. We should point out the alternate possibility of
an additional feedback mechanism that ensures balanced inactivation without
equal
A
and
B
production rates.
