title: Ricin A chain can be chemically cross-linked to the mammalian ribosomal proteins L9 and L10e.
abstract: Indirect immunofluorescence studies revealed that when fixed, permeabilized cultured human cells were incubated with ricin A chain, the toxin molecule localized in a staining pattern indicative of binding to the endoplasmic reticulum and to nucleoli. Chemical cross-linking experiments were performed to identify the cellular components that mediated the binding of ricin A chain. Conjugates were formed between 125I-labeled ricin A chain and two proteins present in preparations of total cell membranes and in samples of purified mammalian ribosomes. Specificity of the ricin A chain-ribosome interaction was demonstrated by inhibition of formation of the complexes by excess unlabeled ricin A chain, but not by excess unlabeled gelonin, another ribosome-inactivating protein. Complexes of ricin A chain cross-linked to the ribosomal proteins were purified and subjected to proteolytic digestion with trypsin. Amino acid sequencing of internal tryptic peptides enabled identification of the ricin A chain-binding proteins as L9 and L10e of the mammalian large ribosomal subunit.
authors.affiliation: ImmunoGen, Inc., Cambridge, Massachusetts 02139-4239, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Vater
authors.forename: L M
authors.initials: LM
authors.lastname: Bartle
authors.forename: J D
authors.initials: JD
authors.lastname: Leszyk
authors.forename: J M
authors.initials: JM
authors.lastname: Lambert
authors.forename: V S
authors.initials: VS
authors.lastname: Goldmacher
mesh_terms: D000595:Amino Acid Sequence; D002451:Cell Compartmentation; D002466:Cell Nucleolus / Q000737:chemistry; D003432:Cross-Linking Reagents; D004721:Endoplasmic Reticulum / Q000737:chemistry; D005455:Fluorescent Antibody Technique; D006801:Humans; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D000080882:Ribosomal Protein L10; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D012276:Ricin / Q000378:metabolism*; D017421:Sequence Analysis; D014407:Tumor Cells, Cultured
chemical_list: D003432:Cross-Linking Reagents; D010750:Phosphoproteins; C000630686:RPL10 protein, human; D012269:Ribosomal Proteins; C049650:ribosomal protein L9; C054675:ribosomal protein P0; D012276:Ricin