title: Interaction of cytochalasin B with actin filaments nucleated or fragmented by villin.
abstract: Villin, a 95,000-dalton protein, is a major component of microvillus cores isolated from intestinal brush borders. In this study, we compared the Ca2+-dependent action of this protein on actin filaments with that of cytochalasin B, a fungal metabolite that binds to the "barbed" end of actin filaments and nuclei. We found that substoichiometric levels of villin inhibit actin filament elongation and self-association in a cytochalasin-like manner. In addition, the protein releases membrane-bound F-actin in the absence of high shear force, probably by severing the filaments. The filament fragments formed in the presence of villin, as well as a nucleating complex consisting of villin and actin, bind stoichiometric amounts of [3H]cytochalasin B with high affinity. The results of this study indicate that both villin and cytochalasin B bind to the same end of actin filaments, yet differ in their binding sites.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002352:Carrier Proteins / Q000494:pharmacology*; D003571:Cytochalasin B / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D009132:Muscles / Q000378:metabolism; D011817:Rabbits
chemical_list: D000199:Actins; D002352:Carrier Proteins; D046911:Macromolecular Substances; D008840:Microfilament Proteins; C026615:villin; D003571:Cytochalasin B; D002118:Calcium