Inhibitors That Block Both the Internalization of Caveolae and the Return of Plasmalemmal Vesicles

Abstract

Potocytosis is an endocytotic process that concentrates and delivers small molecules or ions to the cell interior (Anderson et al. 1992). In some cases, the molecule or ion is a nutrient (Kamen and Capdevila 1986) that the cell needs for viability. Other times, it may be a signaling molecule that provides critical information about the cellular environment (Anderson 1993). The internalization vehicle for potocytosis is the caveola (Rothberg et al. 1990b). Morphological studies have documented that caveolae are dynamic organelles capable of sequestering material from the extracellular environment by forming plasmalemmal vesicles (Simionescu 1983; Parton et al. 1994). These vesicles often do not fuse with vesicles derived from other endocytotic pathways and, in some cells, may not even detach from the plasma membrane. Eventually, these vesicles return to the cell surface and complete the internalization cycle.