A distinct nuclear import pathway used by ribosomal proteins
M P Rout1, G Blobel, J D Aitchison
1Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10021, USA.
Cell
|May 30, 1997
Summary
Researchers discovered a new nuclear import pathway in yeast, mediated by Kap123p, crucial for transporting ribosomal proteins. The related protein Pse1p can also facilitate this essential cellular process.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nuclear transport is essential for eukaryotic cell function.
- Soluble transport factors mediate protein import into the nucleus via nuclear pore complexes.
Purpose of the Study:
- To identify and characterize novel nuclear import pathways in yeast.
- To elucidate the role of uncharacterized proteins in nuclear transport.
Main Methods:
- Yeast genetics and molecular biology techniques.
- Protein binding assays.
- In vivo reporter assays for nuclear localization.
Main Results:
- Identification of a distinct nuclear import pathway mediated by the yeast beta karyopherin Kap123p.
- Kap123p predominantly imports ribosomal proteins, essential for ribosome biogenesis.
- Kap123p directly binds to transport substrates, nucleoporins, and Ran-GTP.
- The related karyopherin Pse1p functionally substitutes for Kap123p.
Conclusions:
- Kap123p represents a major pathway for nuclear import of ribosomal proteins.
- Pse1p also functions as a karyopherin and can mediate ribosomal protein import.
- These findings reveal key mechanisms governing protein transport essential for ribosome assembly.
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