# Structures and Mechanisms of Nuclear Import and Export

> **NIH NIH R01** · UT SOUTHWESTERN MEDICAL CENTER · 2020 · $432,661

## Abstract

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.

## Key facts

- **NIH application ID:** 9847966
- **Project number:** 5R01GM069909-17
- **Recipient organization:** UT SOUTHWESTERN MEDICAL CENTER
- **Principal Investigator:** Yuh Min Chook
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $432,661
- **Award type:** 5
- **Project period:** 2004-02-01 → 2022-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9847966

## Citation

> US National Institutes of Health, RePORTER application 9847966, Structures and Mechanisms of Nuclear Import and Export (5R01GM069909-17). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9847966. Licensed CC0.

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