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Identification of a novel tropomodulin isoform, skeletal tropomodulin, that caps actin filament pointed ends in fast skeletal muscle

Academic Article
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Overview

related to degree

  • Del Tredici, Andria Lee, Ph.D. in Cell Biology, Scripps Research 1993 - 2000

authors

  • Almenar-Queralt, A.
  • Del Tredici, Andria Lee
  • Conley, C. A.
  • Ribas de Pouplana, L.
  • Fowler, Velia

publication date

  • October 1999

journal

  • Journal of Biological Chemistry  Journal

abstract

  • Tropomodulin (E-Tmod) is an actin filament pointed end capping protein that maintains the length of the sarcomeric actin filaments in striated muscle. Here, we describe the identification and characterization of a novel tropomodulin isoform, skeletal tropomodulin (Sk-Tmod) from chickens. Sk-Tmod is 62% identical in amino acid sequence to the previously described chicken E-Tmod and is the product of a different gene. Sk-Tmod isoform sequences are highly conserved across vertebrates and constitute an independent group in the tropomodulin family. In vitro, chicken Sk-Tmod caps actin and tropomyosin-actin filament pointed ends to the same extent as does chicken E-Tmod. However, E- and Sk-Tmods differ in their tissue distribution; Sk-Tmod predominates in fast skeletal muscle fibers, lens, and erythrocytes, while E-Tmod is found in heart and slow skeletal muscle fibers. Additionally, their expression is developmentally regulated during chicken breast muscle differentiation with Sk-Tmod replacing E-Tmod after hatching. Finally, in skeletal muscle fibers that coexpress both Sk- and E-Tmod, they are recruited to different actin filament-containing cytoskeletal structures within the cell: myofibrils and costameres, respectively. All together, these observations support the hypothesis that vertebrates have acquired different tropomodulin isoforms that play distinct roles in vivo.

subject areas

  • Actins
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Carrier Proteins
  • Chick Embryo
  • Chickens
  • DNA, Complementary
  • Microfilament Proteins
  • Molecular Sequence Data
  • Muscle Development
  • Muscle, Skeletal
  • Protein Isoforms
  • Sequence Homology, Amino Acid
  • Spectrin
  • Tropomodulin
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Identity

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.274.40.28466

PubMed ID

  • 10497209
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Additional Document Info

start page

  • 28466

end page

  • 28475

volume

  • 274

issue

  • 40

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