# Mechanisms of kinesin motor protein inhibition: Equipment Supplement

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2024 · $210,000

## Abstract

MECHANISMS OF KINESIN MOTOR PROTEIN INHIBITION
SUMMARY
The spatiotemporal regulation of organelle positioning is critical for proper cellular function, especially as the
cell responds to a changing environment. The kinesin superfamily of motor proteins is responsible for various
cellular processes that range from long-range axonal transport to orchestrating the mitotic spindle during cell
division. The regulation of kinesin motor proteins occurs via inhibitory and activation-based mechanisms,
where kinesin motor proteins are subject to autoinhibition when not bound to a cargo. Recently, the discovery
of kinesin-binding protein (KIFBP) revealed a novel form of kinesin inhibition whereby KIFBP binds to kinesin
motor domains to block microtubule-binding. In this grant, we will determine the molecular basis for
KIFBP-mediated kinesin inhibition in trans and how kinesin light chains in cis-lead to kinesin inhibition. Based
on structural studies of KIFBP bound to two different kinesin motor domains, we developed a model of how
KIFBP remodels kinesin motors and how KIFBP selectively engages motors. We will introduce site-specific
mutagenesis based on crosslinking mass spectrometry and patient-derived mutants to dissect kinesin binding
and remodeling by KIFBP (Aim 1). In parallel, we will determine how light chains regulate full-length kinesin
motor proteins via autoinhibition. Despite decades of work into the regulation of full-length kinesin motor
proteins, there remain conflicting results regarding inhibition of kinesin motor domains. We are poised to
answer this question by exploiting a combination of crosslinking mass spectrometry, protein engineering, and
cryo-EM to determine how kinesin light chains stabilize a compact, inhibited kinesin motor (Aim 2). We will
study both kinesin-1 heterotetramers (KIF5B:KLC1) in addition to kinesin-2 heterotrimers (KIF3A:3B:KAP) to
compare and contrast how these different kinesin motor complexes are autoinhibited. Taken together, this work
will expand our understanding of kinesin regulation, establishing modes of inhibition to provide a complete view
of kinesin activity.

## Key facts

- **NIH application ID:** 11042944
- **Project number:** 3R01GM141119-02S1
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Michael Cianfrocco
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $210,000
- **Award type:** 3
- **Project period:** 2022-09-01 → 2027-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11042944

## Citation

> US National Institutes of Health, RePORTER application 11042944, Mechanisms of kinesin motor protein inhibition: Equipment Supplement (3R01GM141119-02S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/11042944. Licensed CC0.

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