caa a22 4500 463208528 CHVBK 20180405153133.0 cr unu---uuuuu 170326e20070801xx s 000 0 eng 10.1007/s10863-007-9091-0 doi (NATIONALLICENCE)springer-10.1007/s10863-007-9091-0 IF1 distribution in HepG2 cells in relation to ecto-F0F1ATPsynthase and calmodulin [Elektronische Daten] [Stefania Contessi, Marina Comelli, Sara Cmet, Giovanna Lippe, Irene Mavelli] F0F1ATPsynthase is now known to be expressed as a plasma membrane receptor for several extracellular ligands. On hepatocytes, ecto-F0F1ATPsynthase binds apoA-I and triggers HDL endocytosis concomitant with ATP hydrolysis. Considering that inhibitor protein IF1 was shown to regulate the hydrolytic activity of ecto-F0F1ATPsynthase and to interact with calmodulin (CaM) in vitro, we investigated the subcellular distributions of IF1, calmodulin (CaM), OSCP and β subunits of F0F1ATPsynthase in HepG2 cells. Using immunofluorescence and Western blotting, we found that around 50% of total cellular IF1 is localized outside mitochondria, a relevant amount of which is associated to the plasma membrane where we also found Ca2+-CaM, OSCP and β. Confocal microscopy showed that IF1 colocalized with Ca2+-CaM on plasma membrane but not in mitochondria, suggesting that Ca2+-CaM may modulate the cell surface availability of IF1 and thus its ability to inhibit ATP hydrolysis by ecto-F0F1ATPsynthase. These observations support a hypothesis that the IF1-Ca2+-CaM complex, forming on plasma membrane, functions in the cellular regulation of HDL endocytosis by hepatocytes. Springer Science+Business Media, LLC, 2007 HepG2 cells nationallicence Natural inhibitor protein IF1 nationallicence Calmodulin (CaM) nationallicence Ecto-F0F1ATPsynthase nationallicence Mitochondrion nationallicence Plasma membrane nationallicence Contessi Stefania Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut Comelli Marina Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut Cmet Sara Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut Lippe Giovanna Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut Mavelli Irene Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut Journal of Bioenergetics and Biomembranes Springer US; http://www.springer-ny.com 39/4(2007-08-01), 291-300 0145-479X 39:4<291 2007 39 10863 https://doi.org/10.1007/s10863-007-9091-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10863-007-9091-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Contessi Stefania Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut NATIONALLICENCE 700 1- Comelli Marina Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut NATIONALLICENCE 700 1- Cmet Sara Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut NATIONALLICENCE 700 1- Lippe Giovanna Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut NATIONALLICENCE 700 1- Mavelli Irene Department of Biomedical Sciences and Technologies, MATI Centre of Excellence, University of Udine, Piazzale Kolbe 4, 33100, Udine, Italy aut NATIONALLICENCE 773 0- Journal of Bioenergetics and Biomembranes Springer US; http://www.springer-ny.com 39/4(2007-08-01), 291-300 0145-479X 39:4<291 2007 39 10863 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer