Role of the Myosin Assembly Protein UNC-45 as a Molecular Chaperone for Myosin

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Science  25 Jan 2002:
Vol. 295, Issue 5555, pp. 669-671
DOI: 10.1126/science.1066648

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The organization of myosin into motile cellular structures requires precise temporal and spatial regulation. Proteins containing a UCS (UNC-45/CRO1/She4p) domain are necessary for the incorporation of myosin into the contractile ring during cytokinesis and into thick filaments during muscle development. We report that the carboxyl-terminal regions of UNC-45 bound and exerted chaperone activity on the myosin head. The amino-terminal tetratricopeptide repeat domain of UNC-45 bound the molecular chaperone Hsp90. Thus, UNC-45 functions both as a molecular chaperone and as an Hsp90 co-chaperone for myosin, which can explain previous findings of altered assembly and decreased accumulation of myosin in UNC-45 mutants ofCaenorhabditis elegans.

  • * These authors contributed equally to this work.

  • Present address: Max Planck Institute for Biochemistry, D82152 Martinsried, Germany.

  • To whom correspondence should be addressed. E-mail: hepstein{at}

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