IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
artículos
Título:
Autoinhibition mechanism of the plasma membrane calcium pump isoforms 2 and 4 studied through lipid–protein interaction
Autor/es:
GERARDO CORRADI; IRENE C. MANGIALAVORI; D´EBORA E. RINALDI; MAR´ıA CANDELARIA DE LA FUENTE; HUGO P. ADAMO; JUAN PABLO F. C. ROSSI
Revista:
BIOCHEMICAL JOURNAL
Editorial:
PORTLAND PRESS LTD
Referencias:
Lugar: Londres; Año: 2012 vol. 443 p. 125 - 131
ISSN:
0264-6021
Resumen:
The autoinhibition/activation of the PMCA (plasma membraneCa2+ -ATPase) involves conformational changes in the membraneregion of the protein that affect the amount of lipids directlyassociated with the transmembrane domain. The lipid–proteindependenceof PMCA isoforms 2 and 4 expressed and obtainedin purified form from Saccharomyces cerevisiae was investigatedusing the phosphatidylcholine analogue [125I]TID-PC/16{l-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4-(trifluoromemyl-3Hdiazirin-3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine},which was incorporated into mixtures ofdimyristoylphosphatidylcholine and the non-ionic detergentC12E10 [deca(ethylene glycol) dodecyl ether]. We found nodifferences between the recombinant PMCA4 and PMCApurified from erythrocytes (ePMCA). However, titration of thehalf-maximal activation by Ca2+ /calmodulin of PMCA2 showed30-fold higher affinity than PMCA4. PMCA2 exhibited a lowerlevel of labelling in the autoinhibited conformation relative toPMCA4, indicating that the lower autoinhibition was correlatedwith a lower exposure to lipids in the autoinhibited state. Analysisof the lipid–protein stoichiometry showed that the lipid annulus ofPMCA varies: (i) in accordance to the conformational stateof the enzyme; and (ii) depending on the different isoforms ofPMCA. PMCA2 during Ca2+ transport changes its conformationto a lesser extent than PMCA4, an isoform more sensitive tomodulation by calmodulin and acidic phospholipids. This is thefirst demonstration of a dynamic behaviour of annular lipids andPMCA.