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Updated: Jun 29, 2026

Precise Visualization of Insulin Receptors A and B in Murine Brain with an RNA In Situ Hybridization Assay
Published on: July 15, 2025
Differential subcellular localization of insulin receptor substrates depends on C-terminal regions and importin beta
Tomohiro Kabuta1, Kazumi Take, Chihana Kabuta
1Laboratory of Cell Regulation, Departments of Animal Sciences and Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Abstract:
Insulin receptor substrates (IRSs) play essential roles in signal transduction of insulin and insulin-like growth factors. Previously, we showed that IRS-3 is localized to the nucleus as well as the cytosol, while IRS-1 and 2 are mainly localized to the cytoplasm. In the present study, we found that importin beta directly interacts with IRS-3 and is able to mediate nuclear transport of IRS-3. Importin beta interacted with the pleckstrin homology domain, the phosphotyrosine binding domain and the C-terminal region of IRS-3; indeed all of these fragments exhibited predominant nuclear localization. By contrast, almost no interaction of importin beta with IRS-1 and -2 was observed, and their C-terminal regions displayed discrete spotty images in the cytosol. In addition, using chimeric proteins between IRS-1 and IRS-3, we revealed that the C-terminal regions are the main determinants of the differing subcellular localizations of IRS-1 and IRS-3.
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