SEQUESTRATION OF THE G-PROTEIN BETA-GAMMA SUBUNIT COMPLEX INHIBITS RECEPTOR-MEDIATED ENDOCYTOSIS

Cell surface receptors that mediate endocytosis cluster into clathrin- coated pits, which pinch off to form vesicles that transport the recep tors and their ligands. This multi-step process requires the coordinat ed action of many factors, including GTP-hydrolyzing proteins such as dynamin and regulators of actin cytoskeleton assembly. We note herein that sequestration of heterotrimeric G protein beta gamma subunits in intact cells strongly inhibits clathrin-coated pit-mediated endocytosi s and causes rearrangement of the actin cytoskeleton. Our results sugg est that cells contain a pool of free beta gamma and that it functions constitutively to permit endocytosis.