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Author Notes:

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

We thank Andy Fire for the promoter-less GFP vector, Robert Barstead for the random primed nematode cDNA library, and Kozo Kaibuchi (Nagoya University) for vectors pMAL-KK1 and pKK51.

Worm strains were provided by the Caenorhabditis Genetics Center, which is supported by the National Center for Research Resources of the National Institutes of Health.

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Research Funding:

Support for this work was provided by National Institute of Arthritis & Musculoskeletal & Skin Diseases/National Institutes of Health grant AR-051466.

A Novel Protein Phosphatase is a Binding Partner for the Protein Kinase Domains of UNC-89 (Obscurin) in Caenorhabditis elegans

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Journal Title:

Molecular Biology of the Cell

Volume:

Volume 19, Number 6

Publisher:

, Pages 2424-2432

Type of Work:

Article | Final Publisher PDF

Abstract:

Mutation of the Caenorhabditis elegans gene unc-89 results in disorganization of muscle A-bands. unc-89 encodes a giant polypeptide (900 kDa) containing two protein kinase domains, PK1 and PK2. Yeast two-hybrid screening using a portion of UNC-89 including PK2, yielded SCPL-1 (small CTD phosphatase-like-1), which contains a C terminal domain (CTD) phosphatase type domain. In addition to the PK2 domain, interaction with SCPL-1 required the putative autoinhibitory sequence, and immunoglobulin (Ig) and fibronectin type 3 (Fn3) domains lying N-terminal of the kinase domain. SCPL-1 also interacts with PK1, and it similarly requires the kinase domain and upstream Fn3 and Ig domains. Analogous regions from the two other giant kinases of C. elegans, twitchin and TTN-1, failed to interact with SCPL-1. The interaction between SCPL-1 and either Ig-Fn3-PK2 or Fn3-Ig-PK1 was confirmed by biochemical methods. The scpl-1b promoter is expressed in the same set of muscles as unc-89. Antibodies to SCPL-1 localize to the M-line and a portion of the I-band. Bacterially expressed SCPL-1 proteins have phosphatase activity in vitro with properties similar to previously characterized members of the CTD phosphatase family. RNA interference knockdown results in a defect in the function of egg-laying muscles. These studies suggest a new role for the CTD phosphatase family, that is, in muscle giant kinase signaling.

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© 2008 by The American Society for Cell Biology

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