A New Conformation in SERCA and PMCA Ca2+ Pumps Revealed by a Photoactivatable Phospholipidic Probe

IRENE MANGIALAVORI; ANA MARÍA VILLAMIL GIRALDO; CRISTINA MARINO BUSLJE; MARIELA GOMES FERREIRA; ARIEL J. CARIDE; JUAN PABLO F.C. ROSSI

Facultad de Farmacia y Bioquimica

Workshop; International Symposium of the International Master un Biomedical Sciences; 2008

University of Buenos Aires (Argentina) and Albert Ludwigs University of Freiburg (Germany). School of Pharmacy and Biochemistry, UBA. Argentina

.O {color:black; font-size:149%;} a:link {color:#AD1F1F !important;} a:active {color:#A5644E !important;} a:visited {color:#FFC42F !important;} <!--.sld {left:0px !important; width:6.0in !important; height:8.0in !important; font-size:138% !important;} --> Plasma membrane calcium pump (PMCA) is a 134 KDa membrane protein that actively transports Ca2+ towards the plasma membrane. The principal regulatory mechanism of its enzymatic activity is the binding of calmodulin (CaM) to an auto inhibitory domain located near the C-terminus of PMCA. Binding of CaM would lead to the dissociation of this domain causing a large conformational change which results in activation of PMCA. The purpose of this work was to obtain structural information about conformational changes in the membrane regions of PMCA and their interaction with surrounding lipids. We have quantified labeling of the sarcoplasmic reticulum Ca2+ pump (SERCA) and the plasma membrane Ca2+ pump (PMCA) the photoactivatable phosphatidylcholine analog [125I]TID-PC/16, under different conditions. This is because SERCA structure was crystallographically determined (1-2) and it also  belongs to the family of P-type ATPases. Thus, it constitute a model protein as a control for PMCA