Biology Reference
In-Depth Information
¼
A
1
1
D
1
D
2
A
1
F
1
F
2
1
a
21
¼
:
½
8
:
6
a
12
1
1
a
12
a
21
Generally, when the number of fluorescent proteins to be compensated
is
n
, spectral unmixing can be executed by considering an
n
n
matrix and its
inverse as follows:
0
@
1
A
0
@
1
A
F
1
F
2
F
3
.
F
n
D
1
D
2
D
3
.
D
n
¼
A
;
½
8
:
7
0
@
1
A
0
@
1
A
2
4
0
@
1
A
3
5
D
1
D
2
D
3
.
D
n
F
1
F
2
F
3
.
F
n
1
a
21
a
31
a
n
1
a
12
1
a
32
a
n
2
a
13
a
23
1
a
n
3
A
1
¼
,
A
¼
:
½
8
:
8
.
.
.
.
.
.
.
a
1
n
a
2
n
a
3
n
1
In practice, these operations can be performed using commercially avail-
able imaging software.
3. SINGLE-FLUORESCENT PROTEIN-BASED BIOSENSORS
In addition to monitoring protein dynamics or transcriptional activa-
tion (see
Section 2.4
), single-fluorescent protein-based biosensors have also
been used to measure important characteristics of cellular environments, in-
cluding pH, ion flux, and redox potential.
24,35-38
3.1. Fluorescent timers
The processes of chromophore maturation and conversion (see
Sections 2.1
and 2.2
) can be used to create fluorescent proteins with new features. For
example, a red fluorescent protein named drFP583 (E5)
39
changes its
fluorescence from green to red and the recently developed mCherry-
based fluorescent timers
40
convert their spectra from blue to red in a
time-dependent manner. Changes in the emission spectra of these
fluorescent timers are time dependent but concentration independent
because of slow maturation of the chromophore. The predictable time
course of the color change (from blue or green to red) enables
quantitative analysis of temporal and spatial molecular events, thereby
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