Microtubule-associated protein 4 binds to actin filaments and modulates their properties
| Autor: | Mohammad Rubayet Hasan, Kazuyuki Matsushima, Susumu Kotani, Kiyotaka Tokuraku |
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| Rok vydání: | 2011 |
| Předmět: |
Proline
Immunoblotting Molecular Sequence Data Arp2/3 complex macromolecular substances Microtubules Biochemistry Animals Amino Acid Sequence Actin-binding protein Cytoskeleton Molecular Biology Actin Binding Sites Sequence Homology Amino Acid biology Chemistry Actin remodeling EPB41 General Medicine Actin cytoskeleton Actins Peptide Fragments Actin Cytoskeleton Kinetics Microscopy Electron biology.protein Biophysics Cattle Electrophoresis Polyacrylamide Gel MDia1 Microtubule-Associated Proteins Protein Binding |
| Zdroj: | Journal of Biochemistry. 151:99-108 |
| ISSN: | 0021-924X |
| Popis: | We previously reported that an isoform of microtubule-associated protein 4 (MAP4) is localized to the distal area of developing neurites, where microtubules are relatively scarce, raising the possibility that MAP4 interacts with another major cytoskeletal component, actin filaments. In the present study, we examined the in vitro interaction between MAP4 and actin filaments, using bacterially expressed MAP4 and its truncated fragments. Sedimentation assays revealed that MAP4 and its microtubule-binding domain fragments bind to actin filaments under physiological conditions. The apparent dissociation constant and the binding stoichiometry of the fragments to actin were about 0.1 µm and 1 : 3 (MAP4/actin), respectively. Molecular dissection studies revealed that the actin-binding site on MAP4 is situated at the C-terminal part of the proline-rich region, where the microtubule-binding site is also located. Electron microscopy revealed that the MAP4-bound actin filaments become straighter and longer and that the number of actin bundles increases with greater concentrations of added MAP4 fragment, indicating that MAP4 binding alters the properties of the actin filaments. A multiple sequence alignment of the proline-rich regions of MAP4 and tau revealed two putative actin-binding consensus sequences. |
| Databáze: | OpenAIRE |
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