title: Similarity, in molecular structure and function, between the plant toxin purothionin and the mammalian pore-forming proteins.
abstract: Many proteins containing domains of a cysteine-rich repeated motif, such as epidermal growth factor (EGF), have been reported. Here we report strong similarity between the amino acid sequence of a plant toxin--i.e., purothionin and its homologues--and with those of a domain found in mammalian pore-forming cytoplasmic proteins: components of complement and perforin of cytotoxic T-lymphocytes or natural killer-like cytotoxic cells. These similar sequences were found to be identical to the so-called EGF-like cysteine-rich repeated motif itself. Electron-microscopic observations indicated that, like complement and perforin, purothionin forms pores in the cytoplasmic membrane of target cells, resulting in their death within a few hours. On the basis of these sequence comparisons and physiological functions, we propose a scheme for the evolution of proteins containing modules of the cysteine-rich repeat motif.
authors.affiliation: Department of Pathology, Kochi Medical School, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Oka
authors.forename: Y
authors.initials: Y
authors.lastname: Murata
authors.forename: T
authors.initials: T
authors.lastname: Nakanishi
authors.forename: H
authors.initials: H
authors.lastname: Yoshizumi
authors.forename: H
authors.initials: H
authors.lastname: Hayashida
authors.forename: Y
authors.initials: Y
authors.lastname: Ohtsuki
authors.forename: K
authors.initials: K
authors.lastname: Toyoshima
authors.forename: A
authors.initials: A
authors.lastname: Hakura
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D004815:Epidermal Growth Factor / Q000737:chemistry; D006801:Humans; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000737:chemistry*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D015394:Molecular Structure; D054353:Perforin; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D052899:Pore Forming Cytotoxic Proteins; D016415:Sequence Alignment; D014118:Toxins, Biological / Q000737:chemistry* / Q000378:metabolism
chemical_list: D023181:Antimicrobial Cationic Peptides; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010940:Plant Proteins; D052899:Pore Forming Cytotoxic Proteins; D014118:Toxins, Biological; D054353:Perforin; D004815:Epidermal Growth Factor; C016085:purothionin