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Updated: Jun 19, 2026
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Published on: May 4, 2022
Cargo binding induces dimerization of myosin VI.
Denis Phichith1, Mirko Travaglia, Zhaohui Yang
1Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA.
Summary
Myosin VI, a motor protein, functions as a dimer. Cargo binding, through adaptor proteins like optineurin and Dab2, triggers myosin VI dimerization, enabling its cellular functions.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Myosin VI is a unique motor protein that exhibits properties suggesting optimal function as a dimer.
- However, full-length myosin VI is typically observed as a monomer in isolation.
- This discrepancy suggests a regulatory mechanism controlling its dimeric state.
Purpose of the Study:
- To investigate the role of cargo binding in regulating myosin VI dimerization.
- To determine if adaptor proteins can induce dimerization in isolated myosin VI.
- To elucidate the functional consequences of myosin VI dimerization.
Main Methods:
- Expression of myosin VI with known dimeric (optineurin) and monomeric (Dab2) cargo adaptor proteins.
- Biochemical assays to assess ATPase activity.
- Electron microscopy to visualize protein structure.
- In vitro motility assays on actin filaments.
Main Results:
- In the presence of adaptor proteins, full-length myosin VI exhibited ATPase properties characteristic of a dimer.
- Electron microscopy confirmed the dimeric state of myosin VI when bound to adaptors.
- Myosin VI demonstrated processive movement on actin filaments, indicative of dimeric function.
- Unexpectedly, a monomeric fragment of Dab2 also induced myosin VI dimerization.
Conclusions:
- Cargo binding, mediated by adaptor proteins, is a key regulator of myosin VI dimerization.
- Myosin VI is likely designed to function as a dimer in cellular contexts.
- The findings support a model where cargo interaction exposes latent dimerization sequences within myosin VI.
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