Gerald Noel J, Siano Michael, De Lozanne Arturo
Section of Molecular Cell & Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Traffic. 2002 Jan;3(1):50-60. doi: 10.1034/j.1600-0854.2002.30107.x.
LvsA is a Dictyostelium protein that is essential for cytokinesis and that is related to the mammalian beige/LYST family of proteins. To better understand the function of this novel protein family we tagged LvsA with GFP using recombination techniques. GFP-LvsA is primarily associated with the membranes of the contractile vacuole system and it also has a punctate distribution in the cytoplasm. Two markers of the Dictyostelium contractile vacuole, the vacuolar proton pump and calmodulin, show extensive colocalization with GFP-LvsA on contractile vacuole membranes. Interestingly, the association of LvsA with contractile vacuole membranes occurs only during the discharge phase of the vacuole. In LvsA mutants the contractile vacuole becomes disorganized and calmodulin dissociates from the contractile vacuole membranes. Consequently, the contractile vacuole is unable to function normally, it can swell but seems unable to discharge and the LvsA mutants become osmosensitive. These results demonstrate that LvsA can associate transiently with the contractile vacuole membrane compartment and that this association is necessary for the function of the contractile vacuole during osmoregulation. This transient association with specific membrane compartments may be a general property of other BEACH-domain containing proteins.
LvsA是一种盘基网柄菌蛋白，对胞质分裂至关重要，且与哺乳动物的米色蛋白/LYST蛋白家族相关。为了更好地理解这个新蛋白家族的功能，我们利用重组技术用绿色荧光蛋白（GFP）标记了LvsA。GFP-LvsA主要与收缩泡系统的膜相关联，并且在细胞质中也有斑点状分布。盘基网柄菌收缩泡的两个标记物，即液泡质子泵和钙调蛋白，在收缩泡膜上与GFP-LvsA有广泛的共定位。有趣的是，LvsA与收缩泡膜的关联仅发生在液泡的排放阶段。在LvsA突变体中，收缩泡变得紊乱，钙调蛋白从收缩泡膜上解离。因此，收缩泡无法正常发挥功能，它会膨胀但似乎无法排放，并且LvsA突变体对渗透压敏感。这些结果表明，LvsA可以与收缩泡膜区室短暂关联，并且这种关联对于渗透调节过程中收缩泡的功能是必要的。这种与特定膜区室的短暂关联可能是其他含BEACH结构域蛋白的普遍特性。
