title: Identification and characterization of the actin-binding motif of phostensin.
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.
authors: Department of Life Science and Institute of Molecular Biology, National Chung Cheng University, Chia-Yi 62102, Taiwan. thlin@vghtpe.gov.tw.
authors: Tzu-Fan
authors: TF
authors: Wang
authors: Ning-Sheng
authors: NS
authors: Lai
authors: Kuang-Yung
authors: KY
authors: Huang
authors: Hsien-Lu
authors: HL
authors: Huang
authors: Ming-Chi
authors: MC
authors: Lu
authors: Yu-Shan
authors: YS
authors: Lin
authors: Chun-Yu
authors: CY
authors: Chen
authors: Su-Qin
authors: SQ
authors: Liu
authors: Ta-Hsien
authors: TH
authors: Lin
authors: Hsien-Bin
authors: HB
authors: Huang
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D004285:Dogs; D061985:Madin Darby Canine Kidney Cells; D054645:Protein Phosphatase 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D054645:Protein Phosphatase 1