Abstract: Phostensin, a protein phosphatase 1 F-actin cytoskeleton-targeting subunit encoded by KIAA1949, consists of 165 amino acids and caps the pointed ends of actin filaments. Sequence alignment analyses suggest that the C-terminal region of phostensin, spanning residues 129 to 155, contains a consensus actin-binding motif. Here, we have verified the existence of an actin-binding motif in the C-terminal domain of phostensin using colocalization, F-actin co-sedimentation and single filament binding assays. Our data indicate that the N-terminal region of phostensin (1–129) cannot bind to actin filaments and cannot retard the pointed end elongation of gelsolin-actin seeds. Furthermore, the C-terminal region of phostensin (125–165) multiply bind to the sides of actin filaments and lacks the ability to block the pointed end elongation, suggesting that the actin-binding motif is located in the C-terminal region of the phostensin. Further analyses indicate that phostensin binding to the pointed end of actin filament requires N-terminal residues 35 to 51. These results suggest that phostensin might fold into a rigid structure, allowing the N-terminus to sterically hinder the binding of C-terminus to the sides of actin filament, thus rendering phostensin binding to the pointed ends of actin filaments.
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Wang, T.-F.; Lai, N.-S.; Huang, K.-Y.; Huang, H.-L.; Lu, M.-C.; Lin, Y.-S.; Chen, C.-Y.; Liu, S.-Q.; Lin, T.-H.; Huang, H.-B. Identification and Characterization of the Actin-Binding Motif of Phostensin. Int. J. Mol. Sci. 2012, 13, 15967-15982.
Wang T-F, Lai N-S, Huang K-Y, Huang H-L, Lu M-C, Lin Y-S, Chen C-Y, Liu S-Q, Lin T-H, Huang H-B. Identification and Characterization of the Actin-Binding Motif of Phostensin. International Journal of Molecular Sciences. 2012; 13(12):15967-15982.
Wang, Tzu-Fan; Lai, Ning-Sheng; Huang, Kuang-Yung; Huang, Hsien-Lu; Lu, Ming-Chi; Lin, Yu-Shan; Chen, Chun-Yu; Liu, Su-Qin; Lin, Ta-Hsien; Huang, Hsien-Bin. 2012. "Identification and Characterization of the Actin-Binding Motif of Phostensin." Int. J. Mol. Sci. 13, no. 12: 15967-15982.