Identification of specific binding proteins for a nuclear location sequence.
The nuclear envelope is a selective barrier against the movement of macromolecules between the nucleus and cytoplasm. Nuclear proteins larger than relative molecular mass 20,000-40,000 are probably actively transported across the envelope through the nuclear pore complex and are directed by specific nuclear location sequences (NLS) in the proteins. NLS mediate the nuclear import of isolated nuclear proteins after microinjection into whole cells and the nuclear accumulation of chimaeric proteins or of non-nuclear proteins conjugated to synthetic peptides. The best-characterized NLS is the simian virus 40 large T-antigen sequence. We have identified two proteins of rat liver by chemical cross-linking that interact with a synthetic peptide containing this sequence: this interaction is specific for a functional NLS, is saturable, and high affinity. The binding proteins are present in a post-mitochondrial supernatant, in nuclei and in a nuclear envelope fraction, which is consistent with a role in the transport of nuclear proteins from the cytoplasm to the nucleus.
Adam
S A
SA
Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, California 92037.
Lobl
T J
TJ
Mitchell
M A
MA
Gerace
L
L
D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D001665:Binding Sites; D003432:Cross-Linking Reagents / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D013388:Succinimides / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; D003432:Cross-Linking Reagents; D009687:Nuclear Proteins; D013388:Succinimides; C019358:disuccinimidyl suberate