Primary amino acid sequence of alpha-trichosanthin and molecular models for abrin A-chain and alpha-trichosanthin.
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.
Collins
E J
EJ
Department of Chemistry, University of Texas, Austin 78712.
Robertus
J D
JD
LoPresti
M
M
Stone
K L
KL
Williams
K R
KR
Wu
P
P
Hwang
K
K
Piatak
M
M
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
D046911:Macromolecular Substances; D010940:Plant Proteins; D000036:Abrin; D015978:Trichosanthin; D012276:Ricin