title: A gelsolin-like Ca2+-dependent actin-binding domain in villin.
abstract: Villin is an actin-binding protein of relative molecular mass (Mr) 95,000 found in the core bundle of microfilaments in brush border microvilli from intestine. In physiological calcium concentrations (less than 1 microM), villin crosslinks actin filaments into bundles. However, in free calcium concentrations (greater than 1 microM), villin severs actin filaments into short pieces. To understand how villin can sever and bundle actin filaments, we are studying the molecular basis of villin-actin binding interactions by identifying important actin-binding domains in villin. Here, we report the purification and preliminary characterization of a 44,000-Mr fragment of villin which contains a calcium-dependent actin-severing activity. In addition, the partial amino-acid sequence from the amino terminus of this fragment reveals homology with a 16-residue region near the amino terminus of gelsolin, an actin-severing protein found in many cells and sera. The sequence homology suggests a common structural basis for the calcium-regulated actin-severing properties shared by villin and gelsolin.
authors.forename: P
authors.initials: P
authors.lastname: Matsudaira
authors.forename: R
authors.initials: R
authors.lastname: Jakes
authors.forename: J E
authors.initials: JE
authors.lastname: Walker
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000648:ultrastructure; D018260:Gelsolin; D008840:Microfilament Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D008871:Microvilli / Q000378:metabolism; D008970:Molecular Weight; D010446:Peptide Fragments; D013329:Structure-Activity Relationship
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D018260:Gelsolin; D008840:Microfilament Proteins; D010446:Peptide Fragments; C026615:villin; D002118:Calcium