RESUMO

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.

Assuntos

ATPases Transportadoras de Cálcio/metabolismo , Cavéolas/enzimologia , Membrana Celular/enzimologia , Túbulos Renais Proximais/química , Animais , Western Blotting , Cálcio/metabolismo , Calmodulina/metabolismo , Caveolinas/química , Eletroforese em Gel de Poliacrilamida , Microdomínios da Membrana/química , Modelos Biológicos , Suínos