IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
artículos
Título:
Conformational changes produced by ATP binding to the plasma membrane calcium pump.
Autor/es:
MANGIALAVORI IC, FERREIRA-GOMES MS, SAFFIOTI NA, GONZÁLEZ-LEBRERO RM, ROSSI RC, ROSSI JP.
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Referencias:
Lugar: Bethesda, Maryland; Año: 2013 vol. 288 p. 31030 - 31041
ISSN:
0021-9258
Resumen:
The aim of this work was to study the plasma membrane calcium
pump (PMCA) reaction cycle by characterizing conformational changes associated
with calcium, ATP, and vanadate binding to purified PMCA. This was accomplished
by studying the exposure of PMCA to surrounding phospholipids by measuring the
incorporation of the photoactivatable phosphatidylcholine analog 1-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4-(trifluoromethyl-3Hdiazirin-3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine
to the protein. ATP could bind to the different vanadate-bound states of the
enzyme either in the presence or in the absence of Ca2+ with high
apparent affinity. Conformational movements of the ATP binding domain were
determined using the fluorescent analog 2(3)-O-(2,4,6-rinitrophenyl)adenosine 5-triphosphate.Toassess
the conformational behavior of the Ca2+ binding domain, we also
studied the occlusion of Ca2+, both in the presence and in the absence of ATP
and with or without vanadate.
Results show the existence of occluded species in the
presence of vanadate and/or ATP. This allowed the development of a model that
describes the transport of Ca2+ and its relation with ATP hydrolysis.
This is the first approach that uses a conformational study to describe the PMCA
P-type ATPase reaction cycle, adding important features to the classical E1-E2 model
devised using kinetics methodology only.