Effect of different troponin T-tropomyosin combinations on thin filament activation.

Published

Journal Article

The response of permeabilized rabbit fast skeletal muscle fibers to calcium is determined by the troponin T (TnT) and tropomyosin (Tm) isoforms they express. Fibers expressing primarily TnT2f and alpha 2 Tm exhibit steeper pCa/tension relations than those in which either TnT1f or TnT3f and alpha beta Tm predominate. Troponin C extraction studies show that lower slopes do not result from a less concerted transition on the thin filament: the Tn-Tm regulatory strand activates as a unit in all fast fibers. Because the TnT variants differ in their N-terminal segments, and this region overlaps adjacent Tms on the regulatory strand, we propose that both the end-to-end overlap of Tm and the effect of TnT on that interaction are the basis of the concerted transition of the regulatory strand to the active state that occurs in the presence of calcium. Moreover, the effect of different Tn-Tm combinations on the ratio of the affinities of TnC for calcium in the relaxed and active states appears to be a significant determinant of the contractile properties of fast fibers in vivo.

Full Text

Duke Authors

Cited Authors

  • Schachat, FH; Diamond, MS; Brandt, PW

Published Date

  • December 5, 1987

Published In

Volume / Issue

  • 198 / 3

Start / End Page

  • 551 - 554

PubMed ID

  • 3430619

Pubmed Central ID

  • 3430619

International Standard Serial Number (ISSN)

  • 0022-2836

Digital Object Identifier (DOI)

  • 10.1016/0022-2836(87)90300-7

Language

  • eng

Conference Location

  • England