Related Experiment Videos
Nuclear targeting of prothymosin alpha
R E Manrow1, A R Sburlati, J A Hanover
1Section on Genes and Gene Products, National Cancer Institute, Bethesda, Maryland 20892.
The Journal of Biological Chemistry
|February 25, 1991
Summary
Prothymosin alpha, a nuclear protein, is localized to the nucleus via a signal at its carboxyl terminus. This finding clarifies its cellular function and distinguishes it from thymosin alpha 1.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Prothymosin alpha was previously considered a precursor to thymosin alpha 1, a thymus-secreted peptide hormone.
- Its cellular localization and function remained unclear due to the absence of a typical signal peptide.
Purpose of the Study:
- To investigate the cellular localization of prothymosin alpha.
- To identify the specific regions responsible for its nuclear transport.
Main Methods:
- Transfection of COS cells with the human prothymosin alpha gene.
- Enucleation of cells using cytochalasin B and centrifugation.
- Expression of fusion proteins (prothymosin alpha-beta-galactosidase) in COS cells.
- Indirect immunofluorescence microscopy for protein localization.
Main Results:
- Prothymosin alpha was found in the nuclei of transfected COS cells.
- Fusion proteins containing prothymosin alpha sequences were also localized to the nucleus.
- A basic amino acid cluster (TKKQKT) at the carboxyl terminus of prothymosin alpha was identified as a nuclear targeting signal.
Conclusions:
- Prothymosin alpha is a nuclear protein.
- The carboxyl-terminal basic cluster is essential for nuclear localization.
- This nuclear localization mechanism is distinct from that of thymosin alpha 1.