system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, RESULTS. Meshes: Actin-Related Protein 2-3 Complex, Actins, Cell Cycle Proteins, Endocytosis, Microfilament Proteins, Polymerization, Schizosaccharomyces, Schizosaccharomyces pombe Proteins.
user
Does characterization of dip1p reveal a switch in Arp2/3-dependent actin assembly for fission yeast endocytosis? Context: During endocytosis in yeast, a choreographed series of discrete local events at the plasma membrane lead to a rapid burst of actin polymerization and the subsequent internalization of an endocytic vesicle. What initiates Arp2/3-dependent actin polymerization in this process is not well understood. The Schizosaccharomyces pombe WISH/DIP/SPIN90 ortholog dip1p is an actin-patch protein that regulates the temporal sequence of endocytic events. dip1Δ mutants exhibit a novel phenotype in which early events such as WASp localization occur normally but arrival of Arp2/3, actin polymerization, and subsequent steps are delayed and occur with apparently random timing. In studying this mutant, we demonstrate that positive feedback loops of WASp, rapid actin assembly, and Arp2/3 contribute to switch-like behavior that initiates actin polymerization. In the absence of dip1p, a subset of patches is activated concurrently with the "touch" of a neighboring endocytic vesicle.
assistant
These studies reveal a switch-like mechanism responsible for the initiation of actin assembly during endocytosis. This switch may be activated in at least two ways, through a dip1p-dependent mechanism and through contact with another endocytic vesicle. Final Decision: yes