Karyopherin-? (Kap) proteins mediate the majority of protein transport between the nucleus and the cytoplasm. Of the 20 Kaps in human cells, 11 are import-Kaps or Importins, each recognizing a distinct set of protein cargos. This proposal describes structural, biochemical and biophysical analyses of nuclear import systems for core histones H2A/H2B and H3/H4. Here, we propose to understand how histones H2A/H2B are recognized by their primary human importer Importin-9 (Imp9) and by the homologous yeast Kap114. We will determine the mechanisms of how H2A/H2B is recognized by the Importins, how the GTPase Ran interacts with the Importin- H2A/H2B complex and how histone chaperones affect these interactions. We will also study how histones H3/H4 are recognized by their primary human importer, Importin-4 (Imp4). We will explain how histone chaperone Asf1 contributes to nuclear import of H3/H4 and how RanGTP regulates these multi-protein complexes.

Public Health Relevance

Transport of histones into the nucleus is an essential and fundamental cellular process that is immediately downstream of histone synthesis/processing in the cytoplasm and immediately upstream of nucleosome assembly in the nucleus. Steps in histone processing, nuclear import and deposition are likely tightly coordinated. It is therefore important to understand the molecular mechanisms of the individual steps of histone import beyond identification of the Importins and participating histone chaperones. 1

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Flicker, Paula F
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Texas Sw Medical Center Dallas
Schools of Medicine
United States
Zip Code
Fu, Szu-Chin; Fung, Ho Yee Joyce; Ca?atay, Tolga et al. (2018) Correlation of CRM1-NES affinity with nuclear export activity. Mol Biol Cell 29:2037-2044
Ça?atay, Tolga; Chook, Yuh Min (2018) Karyopherins in cancer. Curr Opin Cell Biol 52:30-42
Pinarbasi, Emile S; Ca?atay, Tolga; Fung, Ho Yee Joyce et al. (2018) Active nuclear import and passive nuclear export are the primary determinants of TDP-43 localization. Sci Rep 8:7083
Yoshizawa, Takuya; Ali, Rustam; Jiou, Jenny et al. (2018) Nuclear Import Receptor Inhibits Phase Separation of FUS through Binding to Multiple Sites. Cell 173:693-705.e22
Guo, Lin; Kim, Hong Joo; Wang, Hejia et al. (2018) Nuclear-Import Receptors Reverse Aberrant Phase Transitions of RNA-Binding Proteins with Prion-like Domains. Cell 173:677-692.e20
Fung, Ho Yee Joyce; Fu, Szu-Chin; Chook, Yuh Min (2017) Nuclear export receptor CRM1 recognizes diverse conformations in nuclear export signals. Elife 6:
Volpon, Laurent; Culjkovic-Kraljacic, Biljana; Osborne, Michael J et al. (2016) Importin 8 mediates m7G cap-sensitive nuclear import of the eukaryotic translation initiation factor eIF4E. Proc Natl Acad Sci U S A 113:5263-8
Soniat, Michael; Chook, Yuh Min (2016) Karyopherin-?2 Recognition of a PY-NLS Variant that Lacks the Proline-Tyrosine Motif. Structure 24:1802-1809
Soniat, Michael; Ca?atay, Tolga; Chook, Yuh Min (2016) Recognition Elements in the Histone H3 and H4 Tails for Seven Different Importins. J Biol Chem 291:21171-21183
Hing, Z A; Fung, H Y J; Ranganathan, P et al. (2016) Next-generation XPO1 inhibitor shows improved efficacy and in vivo tolerability in hematological malignancies. Leukemia 30:2364-2372

Showing the most recent 10 out of 33 publications