title: Isolation and characterization of a high molecular weight actin-binding protein from Physarum polycephalum plasmodia.
abstract: A high molecular weight actin-binding protein was isolated from the Physarum polycephalum plasmodia. The protein ( HMWP ) shares many properties with other high molecular weight actin-binding proteins such as spectrin, actin-binding protein from macrophages, and filamin. It has a potent activity to cross-link F-actin into a gel-like structure. Its cross-linking activity does not depend on calcium concentrations. Hydrodynamic studies have revealed that the protein is in the monomeric state of a polypeptide chain with molecular weight of approximately 230,000 in a high ionic strength solvent, while it self-associates into a dimer under physiological ionic conditions. Electron microscopic examinations of HMWP have shown that the monomer particle observed in a high ionic strength solvent is rod shaped with the two-stranded morphology very similar to that of spectrin. On the other hand, under physiological ionic conditions, the HMWP dimer shows the dumb-bell shape with two globular domains connected with a thin flexible strand.
mesh_terms: D000199:Actins / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis; D002352:Carrier Proteins / Q000302:isolation & purification*; D018260:Gelsolin; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D008854:Microscopy, Electron; D008970:Molecular Weight; D010804:Physarum / Q000032:analysis*; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D000199:Actins; D000596:Amino Acids; D002352:Carrier Proteins; D018260:Gelsolin; D046911:Macromolecular Substances; D008840:Microfilament Proteins; C016953:brevin