Actin filament severing by cofilin dismantles actin patches and produces mother filaments for new patches.

摘要: Summary Background: Yeast cells depend on Arp2/3 complex to assemble actin filaments at sites of endocytosis, but the source initial required activate is not known. Results: We tested proposal that cofilin severs during endocytosis in fission yeast using a mutant defective severing. used quantitative fluorescence microscopy track mGFP-tagged proteins, including early endocytic adaptor activators complex, and filaments. Consistent with hypothesis, patches disassembled far more slowly depending severing-deficient than wild-type cells. Even interesting, assembled these Adaptor proteins End4p Pan1p accumulated persisted ten times longer cells, followed by slow persistent recruitment WASP myosin-I. Mutations revealed filament binding contribute initiating polymerization patches. Conclusions: propose ‘‘sever, diffuse, trigger’’ model for nucleation whereby generates fragments diffuse through cytoplasm, bind nascent serve as mother initiate theautocatalytic assembly branched actinfilament network each new patch. This hypothesis explains ‘‘mother filaments’’ are absolutely nucleate polymerization.