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Synthetic peptides as nuclear localization signals.
Nature
|August 14, 1986
Summary
Nuclear localization signals (NLS) guide proteins into the nucleus. A specific SV40 large-T antigen peptide sequence acts as an NLS, demonstrating receptor-mediated nuclear import in Xenopus oocytes.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- The nuclear envelope regulates transport between the nucleus and cytoplasm.
- Specific signals mediate the import and export of molecules like RNA and proteins.
- Nuclear localization signals (NLS) are crucial for nuclear protein targeting.
Purpose of the Study:
- To identify and characterize nuclear localization signals.
- To investigate the mechanism of nuclear protein import.
- To determine if a specific peptide sequence functions as an NLS.
Main Methods:
- Microinjection of cross-linked proteins (BSA, IgG) with synthetic peptides into Xenopus oocytes.
- Site-directed mutagenesis of the SV40 large-T antigen peptide sequence.
- Analysis of protein uptake using anti-peptide antibodies in nuclear and cytoplasmic extracts.
Main Results:
- A 10-residue peptide from SV40 large-T antigen functions as an NLS.
- Substitution at Lys 128 significantly reduces NLS activity.
- Peptide-mediated uptake is saturable and inhibited by free peptide, suggesting a receptor.
Conclusions:
- The identified peptide sequence acts as a functional nuclear localization signal.
- Nuclear import involves a saturable, likely receptor-mediated process.
- Evidence suggests the existence of nuclear proteins recognizing SV40 large-T antigen-like sequences.