Flotillins are lipid raft residents involved in membrane trafficking and recycling of plasma membrane proteins. Dictyostelium discoideum uses phagocytosis to kill, digest and feed on bacteria. It possesses three flotillin-like vacuolins that are strongly associated with membranes and that gradually accumulate on maturing phagosomes. Absence of vacuolins reduced adhesion and particle recognition resulting in a drastic reduction in the uptake of various types of particles. This was caused by a block in the recycling of plasma membrane components and the absence of their specific cortex-associated proteins. In addition, absence of vacuolins also impaired phagolysosome biogenesis, without significantly impacting killing and digestion of a range of bacteria. Strikingly, both absence and overexpression of vacuolins induced a strong downregulation of myosin VII (also known as MyoI) expression, as well as its binding partner talin A. Episomal expression of myosin VII fully rescued defects in uptake and adhesion but not in phagosome maturation. These results suggest a dual role for vacuolins: a novel mechanism involving membrane microdomains and myosin VII–talin A in clustering phagosomal receptors and adhesion molecules at the plasma membrane, and a role in phagolysosomal biogenesis.

Flotillins 是参与膜运输和质膜蛋白回收的脂筏居民。盘基网柄菌利用吞噬作用杀死、消化并以细菌为食。它拥有三个与膜密切相关的类弗洛特林液泡蛋白，并逐渐积累在成熟的吞噬体上。空泡蛋白的缺乏会降低粘附和颗粒识别，导致各种类型颗粒的吸收急剧减少。这是由于质膜成分的回收受阻以及其特定的皮质相关蛋白的缺乏引起的。此外，液泡蛋白的缺失也会损害吞噬溶酶体的生物发生，但不会显着影响一系列细菌的杀灭和消化。引人注目的是，空泡蛋白的缺失和过度表达都会导致肌球蛋白 VII（也称为 MyoI）及其结合伴侣 talin A 表达的强烈下调。肌球蛋白 VII 的附加型表达完全挽救了摄取和粘附的缺陷，但不能挽救吞噬体成熟的缺陷。这些结果表明液泡蛋白具有双重作用：一种涉及膜微结构域和肌球蛋白 VII-talin A 在质膜上聚集吞噬体受体和粘附分子的新机制，以及在吞噬溶酶体生物发生中的作用。