F-actin bundling protein from Physarum polycephalum: purification and its capacity for co-bundling of actin filaments and microtubules.
An F-actin bundling protein was isolated and purified from plasmodium of Physarum polycephalum. The F-actin bundling protein in Physarum extract was passed through a DEAE-cellulose column. After the protein in the fraction was treated with 6 M urea, it was purified by gel filtration on Sephacryl S-300 HR followed by chromatography on CM-Toyopearl (cation exchange) in the presence of 6 M urea. The purified protein gave a single band on SDS-PAGE, and the molecular weight was estimated to be 52,000. This F-actin bundling protein is referred to as the 52 kDa protein. Interestingly, the 52 kDa protein also induced bundling of microtubules. The formation of F-actin and microtubule bundles was Ca(2+)-insensitive, but depended on the salt concentration. Each bundle formed at NaCl concentrations less than 0.1 M. The 52 kDa protein cross-reacted with monoclonal antibody raised against a HeLa 55 kDa protein (an F-actin bundling protein from HeLa cells) (Yamashiro-Matsumura and Matsumura: J. Biol. Chem. 260:5087-5097, 1985). When the 52 kDa protein was added to a mixture of actin filaments and microtubules, co-bundles composed of both filaments formed. This is the first reported example in which an F-actin bundling protein induced co-bundling of actin filaments and microtubules.
Itano
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Department of Molecular Biology, Faculty of Science, Nagoya University, Aichi, Japan.
Hatano
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S
D000199:Actins / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D003429:Cross Reactions; D006367:HeLa Cells / Q000276:immunology; D006801:Humans; D008840:Microfilament Proteins / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D008854:Microscopy, Electron; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D010804:Physarum / Q000737:chemistry* / Q000276:immunology / Q000648:ultrastructure
D000199:Actins; D000911:Antibodies, Monoclonal; D008840:Microfilament Proteins; C052523:actin filament bundling proteins