TY - JOUR
T1 - Plasma membrane calcium pump activity is affected by the membrane protein concentration
T2 - Evidence for the involvement of the actin cytoskeleton
AU - Vanagas, Laura
AU - Rossi, Rolando C.
AU - Caride, Ariel J.
AU - Filoteo, Adelaida G.
AU - Strehler, Emanuel E.
AU - Rossi, Juan Pablo F.C.
N1 - Funding Information:
The present work was supported by the NIH, Fogarty International Center Grant R03TW006837 to EES and JPFCR, NIH grant GM28835 to EES, American Heart Association grant 0130531Z to AJC, and by ANPCYT, CONICET and UBACYT from Argentina.
PY - 2007/6
Y1 - 2007/6
N2 - Plasma membrane calcium pumps (PMCAs) are integral membrane proteins that actively expel Ca2+ from the cell. Specific Ca2+-ATPase activity of erythrocyte membranes increased steeply up to 1.5-5 times when the membrane protein concentration decreased from 50 μg/ml to 1 μg/ml. The activation by dilution was also observed for ATP-dependent Ca2+ uptake into vesicles from Sf9 cells over-expressing the PMCA 4b isoform, confirming that it is a property of the PMCA. Dilution of the protein did not modify the activation by ATP, Ca2+ or Ca2+-calmodulin. Treatment with non-ionic detergents did not abolish the dilution effect, suggesting that it was not due to resealing of the membrane vesicles. Pre-incubation of erythrocyte membranes with Cytochalasin D under conditions that promote actin polymerization abolished the dilution effect. Highly-purified, micellar PMCA showed no dilution effect and was not affected by Cytochalasin D. Taken together, these results suggest that the concentration-dependent behavior of the PMCA activity was due to interactions with cytoskeletal proteins. The dilution effect was also observed with different PMCA isoforms, indicating that this is a general phenomenon for all PMCAs.
AB - Plasma membrane calcium pumps (PMCAs) are integral membrane proteins that actively expel Ca2+ from the cell. Specific Ca2+-ATPase activity of erythrocyte membranes increased steeply up to 1.5-5 times when the membrane protein concentration decreased from 50 μg/ml to 1 μg/ml. The activation by dilution was also observed for ATP-dependent Ca2+ uptake into vesicles from Sf9 cells over-expressing the PMCA 4b isoform, confirming that it is a property of the PMCA. Dilution of the protein did not modify the activation by ATP, Ca2+ or Ca2+-calmodulin. Treatment with non-ionic detergents did not abolish the dilution effect, suggesting that it was not due to resealing of the membrane vesicles. Pre-incubation of erythrocyte membranes with Cytochalasin D under conditions that promote actin polymerization abolished the dilution effect. Highly-purified, micellar PMCA showed no dilution effect and was not affected by Cytochalasin D. Taken together, these results suggest that the concentration-dependent behavior of the PMCA activity was due to interactions with cytoskeletal proteins. The dilution effect was also observed with different PMCA isoforms, indicating that this is a general phenomenon for all PMCAs.
KW - Calcium
KW - Calmodulin
KW - Cytochalasin D
KW - Cytoskeleton
KW - Membrane
KW - PMCA
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U2 - 10.1016/j.bbamem.2007.03.012
DO - 10.1016/j.bbamem.2007.03.012
M3 - Article
C2 - 17481573
AN - SCOPUS:34249088614
SN - 0005-2736
VL - 1768
SP - 1641
EP - 1649
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 6
ER -