title: Primary amino acid sequence of alpha-trichosanthin and molecular models for abrin A-chain and alpha-trichosanthin.
abstract: Ricin A-chain, abrin A-chain, and alpha-trichosanthin are members of a larger group of proteins called ribosome-inactivating proteins. These proteins all function to catalytically inactivate eukaryotic 60 S ribosomal subunits leading to rapid shutdown of protein synthesis. They are homologous in sequence and are probably evolutionarily related. We have determined the complete primary amino acid sequence of alpha-trichosanthin and have found it to be homologous, as expected, to that of abrin A-chain and ricin A-chain. A crystal structure for ricin, which includes ricin A-chain and ricin B-chain, has been determined from x-ray diffraction data. Based on the sequence homologies of these proteins, we fit the primary sequences of abrin A-chain and alpha-trichosanthin to the backbone structure for ricin A-chain and have generated energy-minimized molecular models for them. These models should prove useful in studying the structural-functional relationships of these proteins in particular and of the class in general.
authors.affiliation: Department of Chemistry, University of Texas, Austin 78712.
authors.forename: E J
authors.initials: EJ
authors.lastname: Collins
authors.forename: J D
authors.initials: JD
authors.lastname: Robertus
authors.forename: M
authors.initials: M
authors.lastname: LoPresti
authors.forename: K L
authors.initials: KL
authors.lastname: Stone
authors.forename: K R
authors.initials: KR
authors.lastname: Williams
authors.forename: P
authors.initials: P
authors.lastname: Wu
authors.forename: K
authors.initials: K
authors.lastname: Hwang
authors.forename: M
authors.initials: M
authors.lastname: Piatak
mesh_terms: D000036:Abrin / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics; D011487:Protein Conformation; D012276:Ricin; D012689:Sequence Homology, Nucleic Acid; D015978:Trichosanthin / Q000235:genetics / Q000302:isolation & purification
chemical_list: D046911:Macromolecular Substances; D010940:Plant Proteins; D000036:Abrin; D015978:Trichosanthin; D012276:Ricin