Regulation of coiled-coil assembly in tropomyosins

Esteban Araya, Christine Berthier, Edward Kim, Trevor Yeung, Xiaorong Wang, David M. Helfman

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Tropomyosins (TMs) are a family of actin filament-binding proteins. They consist of nearly 100% α-helix and assemble into parallel coiled-coil dimers. In vertebrates, TMs are encoded by four genes that give rise to at least 17 distinct isoforms through the use of alternative RNA splicing and alternative promoters. We have studied various aspects of the coiled-coil interactions among muscle and nonmuscle isoforms by the use of transfection of epitope-tagged constructs, followed by immunoprecipitation, SDS-PAGE, and Western blot analyses. For coiled-coil interactions between high-molecular-weight isoforms (284 amino acids), the information for homo- versus heterodimerization is contained in large part within the alternatively spliced exons of nonmuscle and muscle (skeletal and smooth) isoforms. Furthermore, sequences located in alternatively spliced exons encoding amino acids 39-80 (exons 2a/2b), amino acids 189-213 (exons 6a/6b), and amino acids 258-284 (exons 9a/9d) are critical for the selective formation of homo- versus heterodimers. Among low-molecular-weight isoforms (248 amino acids), TM-4 and TM-5 can form either homodimers or heterodimers. The trigger sequence (amino acids 190-202) is required for homodimerization of TM-4, but not heterodimerization of TM-4 with TM-5. How the dimeric state of TMs might play a role in their cellular localization and function is discussed.

Original languageEnglish (US)
Pages (from-to)176-183
Number of pages8
JournalJournal of Structural Biology
Issue number1-2
StatePublished - 2002
Externally publishedYes


  • Actin filaments
  • Coiled-coil
  • Cytoskeleton
  • Tropomyosin

ASJC Scopus subject areas

  • Structural Biology


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