Sequence and characterization of cytoplasmic nuclear protein import factor p97

J Cell Biol. 1995 Jul;130(2):265-74. doi: 10.1083/jcb.130.2.265.

Abstract

Nuclear location sequence-mediated binding of karyophilic proteins to the nuclear pore complexes is one of the earliest steps in nuclear protein import. We previously identified two cytosolic proteins that reconstitute this step in a permeabilized cell assay: the 54/56-kD NLS receptor and p97. A monoclonal antibody to p97 localizes the protein to the cytoplasm and the nuclear envelope. p97 is extracted from nuclear envelopes under the same conditions as the O-glycosylated nucleoporins indicating a tight association with the pore complex. The antibody inhibits import in a permeabilized cell assay but does not affect binding of karyophiles to the nuclear pore complex. Immunodepletion of p97 renders the cytosol inactive for import and identifies at least three other cytosolic proteins that interact with p97. cDNA cloning of p97 shows that it is a unique protein containing 23 cysteine residues. Recombinant p97 binds zinc and a bound metal ion is required for the nuclear envelope binding activity of the protein.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal
  • Base Sequence
  • Biological Transport
  • Cattle
  • Cell Line
  • Cloning, Molecular
  • Cytoplasm / chemistry
  • Cytoplasm / metabolism*
  • Molecular Sequence Data
  • Nuclear Envelope / chemistry
  • Nuclear Envelope / metabolism*
  • Nuclear Localization Signals
  • Nuclear Proteins / analysis
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Zinc / metabolism

Substances

  • Antibodies, Monoclonal
  • Nuclear Localization Signals
  • Nuclear Proteins
  • nuclear protein import factor p97
  • Zinc

Associated data

  • GENBANK/L39793