Role of the actin cytoskeleton in regulating the outer phosphatidylethanolamine levels in yeast plasma membrane

Abstract

Transbilayer phosphatidylethanolamine (PtdEtn) movements in the plasma membrane of Saccharomyces cerevisiae are regulated by an ATP-dependent, protein mediated process(es). To examine whether this process is influenced by the actin cytoskeleton, we have studied the PtdEtn translocation in S. cerevisiae cells after treatment with microfilament disrupting and microtubule-disrupting agents. PtdEtn translocation was studied by measuring the external PtdEtn levels, using fluorescamine as the external membrane probe, in the ATP-depleted, ATP-depleted and repleted, and N-ethylmaleimide treated cells. The microfilaments and microtubules were disrupted by treatment with various cytochalasins and colchicines (or benomyl) respectively PtdEtn translocation became abnormal in the cytochalasin-treated cells but not in cells that were treated with microtubule-disrupting agents, such as colchicines or benomyl. These results have been interpreted to suggest that the actin cytoskeleton is involved in regulating the PtdEtn translocase activity in the yeast cell plasma membrane.