Differential actin binding along the PEVK domain of skeletal muscle titin

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45 Citations (Scopus)

Abstract

Parts of the PEVK (Pro-Glu-Val-Lys) domain of the skeletal muscle isoform of the giant intrasarcomeric protein titin have been shown to bind F-actin. However, the mechanisms and physiological function of this are poorly understood. To test for actin binding along PEVK, we expressed contiguous N-terminal (PEVKI), middle (PEVKII), and C-terminal (PEVKIII) PEVK segments of the human soleus muscle isoform. We found a differential actin binding along PEVK in solid-state binding, cross-linking and in vitro motility assays. The order of apparent affinity is PEVKII>PEVKI>PEVKIII. To explore which sequence motifs convey the actin-binding property, we cloned and expressed PEVK fragments with different motif structure: PPAK, polyE-rich and pure polyE fragments. The po]yE-containing fragments had a stronger apparent actin binding, suggesting that a local preponderance of polyE motifs conveys an enhanced local actin-binding property to PEVK. The actin binding of PEVK may serve as a viscous bumper mechanism that limits the velocity of unloaded muscle shortening towards short sarcomere lengths. Variations in the motif structure of PEVK might be a method of regulating the magnitude of the viscous drag.

Original languageEnglish
Pages (from-to)5781-5789
Number of pages9
JournalJournal of cell science
Volume117
Issue number24
DOIs
Publication statusPublished - Nov 15 2004

Keywords

  • Elasticity
  • In vitro motility
  • PEVK
  • PPAK
  • Titin
  • polyE

ASJC Scopus subject areas

  • Cell Biology

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