Related Experiment Video
Updated: Jun 28, 2026

Identification of Nucleolar Factors During HIV-1 Replication Through Rev Immunoprecipitation and Mass Spectrometry
Published on: June 26, 2019
Nuclear Akt interacts with B23/NPM and protects it from proteolytic cleavage, enhancing cell survival
Sang Bae Lee1, Truong L Xuan Nguyen, Joung Woo Choi
1Departments of Molecular Cell Biology and Anatomy and Center for Molecular Medicine, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea.
Abstract:
B23/NPM is a major nucleolar phosphoprotein that has a critical role in cell proliferation and cell death. Here, we show that it forms a complex with Akt on growth factor (GF) stimulation in both the cytoplasm and the nucleus, for which Akt activation is indispensable. The C terminus of B23 (239-294 residues) potently binds pleckstrin homology (PH) domain of Akt. Akt binding to B23 protects it from proteolytic degradation by caspase-3, leading to the up-regulation of cell survival. Interestingly, unsumoylated B23 K263R, but not wild-type B23, strongly interacts with Akt in the nucleoplasm in the absence of GFs. Furthermore, we show that Akt2, but not other isoforms, specifically regulates B23 sumoylation and protein stability. Also, nuclear Akt regulates the cell cycle progression activity of B23. Therefore, our findings support that nuclear Akt binds and stabilizes B23 in the nucleoplasm, and regulates its activities in cell survival and cell cycle.
Related Concept Videos
Regulation of Nuclear Protein Sorting
Nuclear Protein Sorting
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
The Intrinsic Apoptotic Pathway
Negative Regulator Molecules
Nuclear Export
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
Abnormal Proliferation

