title: Identification of a human protein that interacts with nuclear localization signals.
abstract: Through a series of label transfer experiments, we have identified a HeLa cell nuclear protein that interacts with nuclear localization signals (NLSs). The protein has a molecular weight of 66,000 and an isoelectric point of approximately 6. It associates with a synthetic peptide that contains the SV-40 T antigen NLS peptide but not with an analogous peptide in which an asparagine is substituted for an essential lysine (un-NLS peptide). In addition to these peptides, several proteins have been tested as label donors. With the proteins, there is a correlation between nuclear localization (assayed with lysolecithin-permeabilized cells) and label transfer to the 66-kD protein. The NLS peptide (but not the un-NLS peptide) competes with the proteins in label transfer experiments, but neither wheat germ agglutinin nor ATP has an effect. These results suggest that the 66-kD protein functions as an NLS receptor in the first step of nuclear localization. In the course of this work, we have observed that the Staphylococcus aureus protein A is a strongly karyophilic protein. Its dramatic nuclear localization properties suggest that it may have multiple copies of an NLS.
authors.affiliation: Department of Biochemistry, New York University Medical School 10016.
authors.forename: R H
authors.initials: RH
authors.lastname: Li
authors.forename: J O
authors.initials: JO
authors.lastname: Thomas
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002463:Cell Membrane Permeability; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D008244:Lysophosphatidylcholines; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015345:Oligonucleotide Probes; D013205:Staphylococcal Protein A / Q000378:metabolism
chemical_list: D008244:Lysophosphatidylcholines; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D013205:Staphylococcal Protein A