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Interacciones
Proteína - Proteína
Fuertes (t = s, min)
Complejos proteicos (estables)
Débiles (t = ms, ms)
Complejo intermediario (transitorio)
en una reacción enzimática
Interactions between functional groups
Schwikowski et al.(2000) Nature Biotech. 18, 1257 - 1261
Interactions between proteins of different compartments
Schwikowski et al.(2000) Nature Biotech. 18, 1257 - 1261
Yeast SH3 domains — which recognize prolinerich peptides — generated a network containing
394 interactions among 206 proteins
Tong et al. (2002) Science 295, 321-324
An interaction map of the yeast proteome
assembled from published interactions
Schwikowski et al.(2000) Nature Biotech. 18, 1257 - 1261
Protein network in Saccharomyces cerevisiae
..\..\LINKS\Ho Nature(2002).pdf
Ho et al. (2002) Nature 415, 180
Analysing protein interactions:
Systematic identification of protein
complexes in Saccharomyces
cerevisiae by mass spectrometry
Kumar & Snyder (2002) Nature 415, 123-124
Ho, Y et al. (2002) Nature 415, 180 - 183
How does a trimeric G protein on the inside of a cell membrane
respond to activation by a transmembrane receptor?
Trimeric (abg) G
proteins relay signals
from transmembrane
receptors to
intracellular enzymes
and ion channels,
thereby mediating
vision, smell, taste and
the actions of many
hormones and
neurotransmitters
T. Iiri et al. (1998) Nature 394, 35-38
The GTPase cycle of trimeric G proteins
The 'turn-on' step begins when
the activated receptor (R*)
associates with the trimer of
(aGDPbg), causing dissociation of
GDP. Then GTP binds to the
complex of R* with the trimer in
its 'empty' state (aebg), and the
resulting GTP-induced
conformational change causes
aGTP to dissociate from R* and
from bg. After the 'turn-off' step
(hydrolysis of bound GTP to GDP
and inorganic phosphate, Pi),
aGDP reassociates with bg.
T. Iiri et al. (1998) Nature 394, 35-38
Contacts between Gbg (left) and Ga-GDP (right)
Red dashed lines indicate contacts that appear to be required for receptor
activation but not for Ga–Gbg association; green dashed lines indicate
contacts that are important for both functions
T. Iiri et al. (1998) Nature 394, 35-38
How does a trimeric G protein on the inside of a cell membrane
respond to activation by a transmembrane receptor?
Biomedical relevance:
G-protein mutations in
patients with hypertension
and inherited endocrine
disorders enhance or
block signals from
stimulated receptors.
T. Iiri et al. (1998) Nature 394, 35-38
PARP-1: A Perpetrator of
Apoptotic Cell Death
Apoptotic cell death is triggered by
activation of the nuclear enzyme
poly(ADP-ribose) polymerase-1
(PARP-1).
Through unknown mechanisms,
PAR formation and NAD+
depletion may trigger a cascade of
events.
A. Chiarugi & M.A. Moskowitz (2002) Science 297, 200
Fd
OUT
PS II
e*
h
e
IN
PS I
Q
e*
cyt b6-f
complex
Pc (Cu + )
cyt c6 (Fe2+ )
h
e
H2O
Navarro et al. (1997) J. Biol. Inorg. Chem. 2, 11-22
PSI-driven Electron Transfer
light
b6f
Fd
PS I
Pc Cyt c6
Navarro et al. (1997) J. Biol. Inorg. Chem. 2, 11-22
Oxygen content of the earth's atmosphere
Atmospheric Level
(fractions of 21% v/v)
1
Berkner-Marshall Point
(Terrestrial life)
0.1
PROKARYOTES
Pasteur Point
(O2 respiration)
0.01
EUKARYOTES
Photosynthetic
O2 production
0.001
4
3
2
1
Time (109 years ago)
0
(Adapted from Peschek, 1996)
Availability
2-
S
Fe
2-
SO4
Cu
4
3
2
1
Time (109 years ago)
0
(Adapted from Williams & Silva, 1997)
Cu ligands:
His-35 Cys-84
His-87 Met-92
Plastocyanin
Heme ligands:
His-19 Met-61
Cytochrome c6
Isoelectric point of cytochrome c6 and plastocyanin
isolated from different organisms
___________________________________________________
Organism
Protein
pI
___________________________________________________
Spinach
Plastocyanin
4.2
Monoraphidium
Plastocyanin
Cytochrome c6
3.7
3.6
Anabaena
Plastocyanin
Cytochrome c6
9.0
9.0
Synechocystis
Plastocyanin
Cytochrome c6
5.5
5.6
____________________________________________________
Cytochrome c6
Plastocyanin
De la Rosa et al. (2002) Bioelectrochemistry 55, 41-45
Photosynthetic
organisms growing
under controlled
conditions
DA = 2 x 10-3
KA
Protred + PSIred
1
KR
[Protred ... PSIred]
2
h
[Protred ... PSIred]*
h
K'A
Protred + PSIox
1'
3
h
K' R
[Protred ... PSIox ]
[Protred ... PSIox ]*
2'
3'
ket
Routes
a:
b:
c:
1 h 1'
1
2 h
1
2
2'
2'
h
3
3'
3'
3'
4
4
4
Protox + PSIred
4
De la Rosa et al. (2002) Bioelectrochemistry 55, 41-45
KINETIC TYPES FOR THE REACTION MECHANISM
Type I
Protred + PSIox  Protox + PSIred
Type II
Protred + PSIox [Protred ... PSIox]  Protox + PSIred
Type III
Protred + PSIox [Protred ... PSIox] [Protred ... PSIox]*  Protox + PSIred
Navarro et al. (1997) J. Biol. Inorg. Chem. 2, 11-22
Flexibilidad estructural de la plastocianina