title: Involvement of a 40-kDa glycoprotein in food recognition, prey capture, and induction of phagocytosis in the protozoon Actinophrys sol.
abstract: A 40-kDa glycoprotein (gp40) was identified as a Con A-binding adhesive substance of the heliozoon Actinophrys sol for immobilizing and ingesting prey flagellates. Isolation and partial characterization of gp40 showed that: 1) gp40 is a major Con A-binding protein of Actinophrys with a molecular weight of 40 kDa, and is stored in secretory granules called extrusomes; 2) gp40 was purified by Con A-affinity chromatography, and the N-terminal amino acid sequence was determined as H2N-KVLK-FEDDFDTFDLQ; 3) prey flagellates became adhered to gp40-immobilized agarose beads; 4) phagocytosis of Actinophrys was induced against gp40-immobilized agarose beads; and 5) solubilized gp40 induced exocytosis of extrusomes and cell fusion of heliozoons. These results indicate that gp40 is a multi-functional secretory protein of Actinophrys, which is required in correct targeting of the heliozoon to food organisms as well as in self-recognition.
authors.affiliation: Department of Biology, Faculty of Science, Kobe University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Sakaguchi
authors.forename: H
authors.initials: H
authors.lastname: Murakami
authors.forename: T
authors.initials: T
authors.lastname: Suzaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002846:Chromatography, Affinity; D003208:Concanavalin A; D056890:Eukaryota / Q000502:physiology*; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry; D010587:Phagocytosis; D011235:Predatory Behavior; D015800:Protozoan Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology*; D022142:Secretory Vesicles / Q000502:physiology
chemical_list: D006023:Glycoproteins; D010446:Peptide Fragments; D015800:Protozoan Proteins; D003208:Concanavalin A