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Author Notes:

Address correspondence to: Guy Benian (pathgb@emory.edu).

We thank Anne Schwager and Tony Hyman (Max-Planck Institute, Dresden, Germany) for antibodies to RSA-1 and Kevin O’Connell (National Institutes of Health) for antibodies to SUR-6.

We thank Robert Barstead (Oklahoma Medical Research Foundation) for the C. elegans yeast two-hybrid library RB2 and Yuji Kohara (National Institute of Genetics, Japan) for “yk” cDNA clones.

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Research Funding:

This study was supported in part by the Emory Integrated Proteomics Core (EIPC), which is subsidized by the Emory University School of Medicine and is one of the Emory Integrated Core Facilities.

This work was also supported by the Georgia Institute of Technology’s Parker H. Petit Institute for Bioengineering and Bioscience, including the Systems Mass Spectrometry Core Facility.

This study was supported by grants from the National Institutes of Health (R01 AR064307 to G.M.B. and R01 CA57327 to D.C.P.).

Many of the nematode strains used in this work were provided by the Caenorhabditis Genetics Center, which is funded by the NIH Office of Research Infrastructure Programs (P40 OD010440).

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Cell Biology
  • MYOSIN HEAVY-CHAIN
  • BODY-WALL MUSCLE
  • C-ELEGANS
  • THICK FILAMENTS
  • UNC-89 OBSCURIN
  • DOMAIN PROTEIN
  • KINASE DOMAINS
  • M-LINE
  • PHOSPHORYLATION
  • PARAMYOSIN

Protein phosphatase 2A is crucial for sarcomere organization in Caenorhabditis elegans striated muscle

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Journal Title:

Molecular Biology of the Cell

Volume:

Volume 29, Number 17

Publisher:

, Pages 2084-2097

Type of Work:

Article | Final Publisher PDF

Abstract:

Protein phosphatase 2A (PP2A) is a heterotrimer composed of single catalytic and scaffolding subunits and one of several possible regulatory subunits. We identified PPTR-2, a regulatory subunit of PP2A, as a binding partner for the giant muscle protein UNC-89 (obscurin) in Caenorhabditis elegans. PPTR-2 is required for sarcomere organization when its paralogue, PPTR-1, is deficient. PPTR-2 localizes to the sarcomere at dense bodies and M-lines, colocalizing with UNC-89 at M-lines. PP2A components in C. elegans include one catalytic subunit LET-92, one scaffolding subunit (PAA-1), and five regulatory subunits (SUR-6, PPTR-1, PPTR-2, RSA-1, and CASH-1). In adult muscle, loss of function in any of these subunits results in sarcomere disorganization. rsa-1 mutants show an interesting phenotype: One of the two myosin heavy chains, MHC A, localizes as closely spaced double lines rather than single lines. This "double line" phenotype is found in rare missense mutants of the head domain of MHC B myosin, such as unc-54(s74). Analysis of phosphoproteins in the unc-54(s74) mutant revealed two additional phosphoserines in the nonhelical tailpiece of MHC A. Antibodies localize PPTR-1, PAA-1, and SUR-6 to I-bands and RSA-1 to M-lines and I-bands. Therefore, PP2A localizes to sarcomeres and functions in the assembly or maintenance of sarcomeres.

Copyright information:

© 2018 Qadota et al.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License (http://creativecommons.org/licenses/by-nc-sa/3.0/).

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