title: Ribosomal protein S18 identified as a cofilin-binding protein by using phage display library.
abstract: We previously reported that an actin-binding protein, cofilin, is involved in superoxide production, phagocytosis, and chemotaxis in activated phagocytes through cytoskeletal reorganization. To elucidate the functions of cofilin in greater detail we tried to identify cofilin-binding proteins by using a phage-displayed cDNA library constructed from human brain mRNAs. Several phage clones capable of binding to cofilin were obtained, and the phage with the strongest binding affinity contained the C-terminal half of ribosomal protein S18. To confirm the interaction between the S18 protein and cofilin, we investigated whether cofilin would bind to His-tagged S18 protein immobilized in Ni-NTA-agarose gel. Cofilin and the S18 protein co-eluted with a low pH (4.5) buffer, suggesting that the proteins interact with each other. Preincubation of cofilin with actin abrogated the binding to protein S18, indicating that cofilin interacts with S18 protein at the actin-binding site, and cofilin co-immunoprecipitated with FLAG-tagged S18 protein expressed in COS-7 cells. These results suggest that some cofilin molecules bind the ribosomal S18 protein under physiological conditions.
authors.affiliation: National Institute of Health Sciences, Kamiyoga, Setagaya-ku, Tokyo, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kusui
authors.forename: Haruyo
authors.initials: H
authors.lastname: Sasaki
authors.forename: Reiko
authors.initials: R
authors.lastname: Adachi
authors.forename: Sachiko
authors.initials: S
authors.lastname: Matsui
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Teruhide
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kasahara
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D003599:Cytoskeleton; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism*; D019151:Peptide Library; D011485:Protein Binding; D025941:Protein Interaction Mapping; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D008840:Microfilament Proteins; D019151:Peptide Library; D012269:Ribosomal Proteins; C041184:ribosomal protein S18