INVESTIGADORES
ROSSI juan pablo Francisco
congresos y reuniones científicas
Título:
A New Conformation in SERCA and PMCA Ca2+ Pumps Revealed by a Photoactivatable Phospholipidic Probe
Autor/es:
IRENE MANGIALAVORI, ANA MARÍA VILLAMIL GIRALDO, CRISTINA MARINO BUSLJE, MARIELA GOMES FERREIRA, ARIEL J. CARIDE AND JUAN PABLO F.C. ROSSI
Lugar:
Boston, Massachusetts-USA.
Reunión:
Congreso; 3rd Annual Meeting of Biophysical Society.; 2009
Institución organizadora:
Biophysical Society
Resumen:
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The purpose of this work was to obtain structural information about
conformational changes of the plasma membrane Ca2+ pump (PMCA) in
the membrane region upon interaction with ATP, Ca2+, calmodulin and
acidic phospholipids. To this end, we have quantified labeling of PMCA with the
photoactivatable phosphatidylcholine analog [125I]TID-PC/16,
measuring the shift of conformation E2 to the auto-inhibited
conformation E1I and to the activated E1A state, titrating
the effect of Ca2+ and ATP under different conditions. With this
method we were able to measure apparent and equilibrium constants for the
dissociation of Ca2+, ATP and calmodulin and other ligands from PMCA
complexes through the change of transmembrane conformations of the pump. The
results indicate that the PMCA possesses a high-affinity site for Ca2+ regardless
of the presence or absence of activators. Modulation of pump activity is
exerted through the C-terminal domain, which induces an apparent auto-inhibited
conformation for Ca2+ transport but does not modify the affinity for
Ca2+ at the transmembrane domain. The C-terminal domain is affected
by calmodulin and calmodulin-like treatments driving the auto-inhibited
conformation E1I to the activated E1A conformation and
thus modulating the transport of Ca2+. The data further suggest that
the hydrophobic transmembrane domain of the PMCA undergoes major rearrangements
resulting in altered lipid accessibility upon Ca2+ binding and
activation. With grants
from ANPCYT, CONICET, UBACYT and NIH.