Vacuolar-Type H+ -ATPases Are Associated with the Endoplasmic Reticulum and Provacuoles of Root Tip Cells

摘要: To understand the origin of vacuolar H+ -ATPases (V-ATPases) and their cellular functions, subcellular location V-H+ was examined immunologically in root cells oat seedlings. A V-ATPase complex from roots consists a large peripheral sector (V1) that includes 70-kD (A) catalytic 60-kD (B) regulatory subunits. The soluble V1 complex, thought to be synthesized cytoplasm, is assembled with membrane integral (V0) at yet undefined location. In mature cells, subunits B, detected immunoblots monoclonal antibodies (Mab) (7A5 2E7), were associated mainly membranes (20–22% sucrose) fractionated an isopycnic sucrose gradient. However, immature tip which lack vacuoles, most localized endoplasmic reticulum (ER) 28 31% where major ER-resident binding protein equilibrated. also 22% sucrose, 31 34% (Golgi), plasma 38% sucrose. Immunogold labeling Mab 2E7 against subunit B showed gold particles decorating ER as well numerous small vesicles (0.1–0.3 [mu]m diameter), presumably pro-vacuoles. immunological detection on supports model V0 ER. These results support central originates ultimately presence V-ATPases several endomembranes indicates this pump could participate diverse functional roles.