# Reconstitution and biophysical study of chromosome segregation machinery

> **NIH GM R35** · UNIVERSITY OF WASHINGTON · 2026 · $727,855

## Abstract

PROJECT SUMMARY
An exquisite molecular machine, the mitotic spindle, separates duplicated chromosomes during cell division. To
uncover how it operates, we are reconstituting spindle activities using purified components and developing
biophysical tools to directly manipulate and track their dynamics at the single molecule level. The accuracy of
eukaryotic chromosome segregation is incredible and depends critically on kinetochores, which are multiprotein
complexes that maintain strong yet dynamic attachments between chromosomes and spindle microtubules in
order to produce force and move the chromosomes. Kinetochores also carry out vital regulatory activities such
as distinguishing and selectively stabilizing proper attachments, releasing erroneous attachments, and
generating diffusible ‘wait’ signals to delay mitosis until proper attachments are achieved. Our reconstitution-
based approach has enabled the first direct measurements of many fundamental kinetochore activities and direct
tests of long-standing hypotheses from cytological studies, proving for example that tension stabilizes
kinetochore attachments in at least two different ways. Our work has also revealed previously unrecognized
kinetochore behaviors and motivated new genetic, cytological, and structural studies. Our preliminary data now
reveal another striking and previously unrecognized behavior: yeast kinetochores grip the sides of microtubules
with directionally asymmetric strength – much more strongly when pulled toward plus ends than when pulled
toward minus ends. This asymmetric grip strength is likely to promote proper attachments in early mitosis when
kinetochores first bind the sides of microtubules. We will uncover its molecular basis, test its conservation in
human kinetochores, determine how it relates to the catch bond-like activity we previously uncovered and to the
widely studied kinase-based mechanism for correcting erroneous attachments, and ultimately develop a new
integrated explanation

## Key facts

- **NIH application ID:** 11314503
- **Project number:** 5R35GM134842-07
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Charles L Asbury
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** GM
- **Fiscal year:** 2026
- **Award amount:** $727,855
- **Award type:** 5
- **Project period:** 2020-01-01T00:00:00 → 2030-03-31T00:00:00

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11314503

## Citation

> US National Institutes of Health, RePORTER application 11314503, Reconstitution and biophysical study of chromosome segregation machinery (5R35GM134842-07). Retrieved via AI Analytics 2026-07-06 from https://api.ai-analytics.org/grant/nih/11314503. Licensed CC0.

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