title: Inhibition of nuclear protein import by a monoclonal antibody against a novel class of nuclear pore proteins.
abstract: Nuclear import of proteins is mediated by the nuclear pore complexes in the nuclear envelope and requires the presence of a nuclear localization signal (NLS) on the karyophilic protein. In this paper, we describe studies with a monoclonal antibody, Mab E2, which recognizes a class of nuclear pore proteins of 60-76 kDa with a common phosphorylated epitope on rat nuclear envelopes. The Mab E2-reactive proteins fractionated with the relatively insoluble pore complex-containing component of the envelope and gave a finely punctate pattern of nuclear staining in immunofluorescence assays. The antibody did not bind to any cytosolic proteins. Mab E2 inhibited the interaction of a simian virus 40 large T antigen NLS peptide with a specific 60-kDa NLS-binding protein from rat nuclear envelopes in photoaffinity labeling experiments. The antibody blocked the nuclear import of NLS-albumin conjugates in an in vitro nuclear transport assay with digitonin-permeabilized cells, but did not affect passive diffusion of a small non-nuclear protein, lysozyme, across the pore. Mab E2 may inhibit protein transport by directly interacting with the 60-kDa NLS-binding protein, thereby blocking signal-mediated nuclear import across the nuclear pore complex.
authors.affiliation: Centre for Cellular and Molecular Biology, Hyderabad, India.
authors.forename: S
authors.initials: S
authors.lastname: Pandey
authors.forename: A A
authors.initials: AA
authors.lastname: Karande
authors.forename: K
authors.initials: K
authors.lastname: Mishra
authors.forename: V K
authors.initials: VK
authors.lastname: Parnaik
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001692:Biological Transport / Q000187:drug effects; D002451:Cell Compartmentation; D002478:Cells, Cultured; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000737:chemistry / Q000378:metabolism*; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism; D051381:Rats
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D009687:Nuclear Proteins; D010455:Peptides; D010750:Phosphoproteins