# Motor properties and regulation of human myosin 3B

> **NIH NIH F32** · PENNSYLVANIA STATE UNIV HERSHEY MED CTR · 2021 · $14,652

## Abstract

Abstract:
The objective of this proposal is to better understand the properties of Myo3B and its role as a
transporter in actin bundle based structures such as the stereocilia of inner ear hair cells. Class III
myosins are known actin based motors and are unique because they contain an N-terminal kinase
domain that serves to autoregulate motor activity. In vertebrates there exists two class III myosin
isoforms; Myo3A and Myo3B. Class III myosins are expressed in inner ear hair cells, photoreceptors,
brain, testis, and intestines. Both Myo3A and Myo3B have been shown to bind the actin bundling
protein Espin and transport it to the tips of actin protrusions to promote elongation. Myo3A harbors
deafness associated mutations while Myo3B is proposed to partially compensate for lack of functional
Myo3A, which results in delayed onset deafness. In addition, we recently discovered that Myo3B is
strongly regulated by physiological concentrations of calcium, while Myo3A is not. Therefore, it is
crucial to characterize the intrinsic motor properties of the Myo3B motor and understand how it is
calcium regulated to determine its function in parallel actin based structures. We will investigate the
calcium regulation of Myo3B with in vitro assays such as steady-state ATPase, in vitro motility, and
transient kinetic analysis with purified proteins which will allow us to determine the intrinsic motor
properties of MYO3B. In addition, cell biological studies using cultured cells will enable us to examine
the calcium regulation of Myo3B localization and impact on actin protrusion dynamics. Overall, this
study will provide fundamental information about the motor mechanism of Myo3B, which will reveal
crucial information about its function in the stereocilia of inner ear hair cells.

## Key facts

- **NIH application ID:** 10371409
- **Project number:** 3F32DC016788-03S1
- **Recipient organization:** PENNSYLVANIA STATE UNIV HERSHEY MED CTR
- **Principal Investigator:** Laura Kay Gunther
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $14,652
- **Award type:** 3
- **Project period:** 2018-06-01 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10371409

## Citation

> US National Institutes of Health, RePORTER application 10371409, Motor properties and regulation of human myosin 3B (3F32DC016788-03S1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10371409. Licensed CC0.

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