JCB logo
amgmicro.com
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 944K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Barral, J. M.
Right arrow Articles by Epstein, H. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Barral, J. M.
Right arrow Articles by Epstein, H. F.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

© The Rockefeller University Press, 0021-9525/1998//1215 $5.00
The Journal of Cell Biology, Volume 143, Number 5, , 1998 1215-1225

Article

Unc-45 Mutations in Caenorhabditis elegans Implicate a CRO1/She4p-like Domain in Myosin Assembly



José M. Barral*, Christopher C. Bauer{ddagger}, Irving Ortiz{ddagger}, and Henry F. Epstein*,{ddagger}

* Department of Biochemistry and {ddagger} Department of Neurology, Baylor College of Medicine, Houston, Texas 77030

The Caenorhabditis elegans unc-45 locus has been proposed to encode a protein machine for myosin assembly. The UNC-45 protein is predicted to contain an NH2-terminal domain with three tetratricopeptide repeat motifs, a unique central region, and a COOH-terminal domain homologous to CRO1 and She4p. CRO1 and She4p are fungal proteins required for the segregation of other molecules in budding, endocytosis, and septation. Three mutations that lead to temperature-sensitive (ts) alleles have been localized to conserved residues within the CRO1/She4p-like domain, and two lethal alleles were found to result from stop codon mutations in the central region that would prevent translation of the COOH-terminal domain. Electron microscopy shows that thick filament accumulation in vivo is decreased by ~50% in the CB286 ts mutant grown at the restrictive temperature. The thick filaments that assemble have abnormal structure. Immunofluorescence and immunoelectron microscopy show that myosins A and B are scrambled, in contrast to their assembly into distinct regions at the permissive temperature and in wild type. This abnormal structure correlates with the high degree of instability of the filaments in vitro as reflected by their extremely low yields and shortened lengths upon isolation. These results implicate the UNC-45 CRO1/She4p-like region in the assembly of myosin isoforms in C. elegans and suggest a possible common mechanism for the function of this UCS (UNC-45/CRO1/She4p) protein family.

Key Words: myosin • muscle • chaperone • biosynthesis • Caenorhabditis elegans

Abbreviations used in this paper: CCM, chemical cleavage of mismatches; F1, first generation; F2, second generation; GS, goat serum; IB, isolation buffer; let, constitutive lethal; mhc, myosin heavy chain; mr, maternally rescuable lethal; TBST, Tris buffered saline + Tween 20; TPR, tetratricopeptide repeat; ts, temperature sensitive; Unc, uncoordinated.

Address all correspondence to Dr. Henry F. Epstein, Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030. Tel.: (713) 798-4629. Fax: (713) 798-3771. E-mail: hepstein{at}bcm.tmc.edu


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents