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Updated: May 3, 2026
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In vivo and in vitro Studies of Adaptor-clathrin Interaction
Published on: January 26, 2011
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Structure of a myosin•adaptor complex and pairing by cargo
Hang Shi1, Nimisha Singh, Filipp Esselborn
1Laboratory of Cell Biology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065.
Summary
Yeast Myosin 4 (Myo4p) and adaptor She3p form a heterotrimer. Cargo binding induces dimerization of two Myo4p•She3p complexes, forming a transport-competent motor for cytoplasmic cargo delivery.
Area of Science:
- Cell biology
- Molecular motors
- Protein structure and function
Background:
- Myosin 4 protein (Myo4p) in yeast mediates cytoplasmic transport of messenger ribonucleoprotein particles (mRNPs) and tubular endoplasmic reticulum (tER).
- The adaptor protein She3p links Myo4p to these cargos, but the assembly of a functional transport complex is not well understood.
Purpose of the Study:
- To elucidate the structural basis of Myo4p-She3p complex formation and cargo-induced activation.
- To propose a model for the assembly of a transport-competent motor complex.
Main Methods:
- X-ray crystallography to determine the structure of Myo4p•She3p complexes.
- Biochemical reconstitution assays to study complex assembly and cargo binding.
Main Results:
- Myo4p and She3p form a stable 1:2 heterotrimer in solution, with a crystal structure revealing specific interaction interfaces.
- The Myo4p•She3p heterotrimer alone is not transport-competent.
- Cargo binding, mediated by zipcode binding protein She2p, induces dimerization of two Myo4p•She3p heterotrimers, creating a two-myosin motor complex.
Conclusions:
- Cargo binding is essential for generating a transport-competent motor complex by linking two Myo4p•She3p units.
- A conserved region on She3p is a potential binding site for tubular endoplasmic reticulum (tER).
- This mechanism allows for the coordinated transport of mRNPs and tER.
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