The plasma membrane Ca2+ pump from proximal kidney tubules is exclusively localized and active in caveolae.
Plasma membrane Ca2+-ATPase is involved in the fine-tuned regulation of intracellular Ca2+. In this study, the presence of Ca2+-ATPase in caveolae from kidney basolateral membranes was investigated. With the use of a discontinuous sucrose gradient, we show that Ca2+-ATPase is exclusively located and fully active in caveolin-containing microdomains. Treatment with methyl-beta-cyclodextrin--a cholesterol chelator--leads to a spreading of both caveolin and completely inactive Ca2+-ATPase toward high-density fractions. These data support the view that Ca2+ fluxes mediated by Ca2+-ATPase in kidney epithelial cells occur only in caveolae, being strictly dependent on the integrity of these microdomains.
Laboratório de Físico-Química Biológica Aída Hassón-Voloch, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21949-900 Ilha do Fundão, Rio de Janeiro, Brazil.
Giovane G
GG
Tortelote
Rafael H F
RH
Valverde
Thiago
T
Lemos
Adílson
A
Guilherme
Marcelo
M
Einicker-Lamas
Adalberto
A
Vieyra
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D021941:Caveolae / Q000201:enzymology*; D022461:Caveolins / Q000737:chemistry; D002462:Cell Membrane / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D007687:Kidney Tubules, Proximal / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry; D008954:Models, Biological; D013552:Swine
D002147:Calmodulin; D022461:Caveolins; D000252:Calcium-Transporting ATPases; D002118:Calcium