title: An Atypical Tropomyosin in Drosophila with Intermediate Filament-like Properties.
abstract: A longstanding mystery has been the absence of cytoplasmic intermediate filaments (IFs) from Drosophila despite their importance in other organisms. In the course of characterizing the in vivo expression and functions of Drosophila Tropomyosin (Tm) isoforms, we discovered an essential but unusual product of the Tm1 locus, Tm1-I/C, which resembles an IF protein in some respects. Like IFs, Tm1-I/C spontaneously forms filaments in vitro that are intermediate in diameter between F-actin and microtubules. Like IFs but unlike canonical Tms, Tm1-I/C contains N- and C-terminal low-complexity domains flanking a central coiled coil. In vivo, Tm1-I/C forms cytoplasmic filaments that do not associate with F-actin or canonical Tms. Tm1-I/C is essential for collective border cell migration, in epithelial cells for proper cytoarchitecture, and in the germline for the formation of germ plasm. These results suggest that flies have evolved a distinctive type of cytoskeletal filament from Tm.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Department of Biological Chemistry, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
authors.forename: Aeri
authors.initials: A
authors.lastname: Cho
authors.affiliation: Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9152, USA.
authors.forename: Masato
authors.initials: M
authors.lastname: Kato
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
authors.forename: Tess
authors.initials: T
authors.lastname: Whitwam
authors.affiliation: Department of Biological Chemistry, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Department of Biological Chemistry, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA. Electronic address: denise.montell@lifesci.ucsb.edu.
authors.forename: Denise J
authors.initials: DJ
authors.lastname: Montell
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002465:Cell Movement / Q000502:physiology; D003599:Cytoskeleton / Q000378:metabolism; D004330:Drosophila / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005260:Female; D005854:Germ Cells / Q000378:metabolism / Q000502:physiology; D007382:Intermediate Filaments / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D014335:Tropomyosin / Q000378:metabolism*
chemical_list: D000199:Actins; D020033:Protein Isoforms; D014335:Tropomyosin