Role of tropomyosin isoforms in the calcium sensitivity of striated muscle thin filaments

Boussouf, Sabrina and Maytum, Robin and Jaquet, Kornelia and Geeves, Michael A. (2007) Role of tropomyosin isoforms in the calcium sensitivity of striated muscle thin filaments. Journal of Muscle Research and Cell Motility, 28 (1). pp. 49-58. ISSN 0142-4319 . (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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We have expressed alpha & beta isoforms of mammalian striated muscle tropomyosin (Tm) and alpha-Tm carrying the D175N or E180G cardiomyopathy mutations. In each case the Tm carries an Ala-Ser N-terminal extension to mimic the acetylation of the native Tm. We show that these Ala-Ser modified proteins are good analogues of the native Tm in the assays used here. We go on to use an in vitro kinetic approach to define the assembly of actin filaments with the Tm isoforms with either a cardiac or a skeletal muscle troponin (cTn, skTn). With skTn the calcium sensitivity of the actin filament is the same for alpha & beta-Tm and there is little change with the mutant Tms. For cTn switching from alpha to beta-Tm causes an increase of calcium sensitivity of 0.2 pCa units. D175N is very similar to the wild type alpha-Tm and E180G shows a small increase in calcium sensitivity of about 0.1 pCa unit. The formation of the switched-off blocked-state of the actin filament is independent of the Tm isoform but does differ for cardiac versus skeletal Tn. The in vitro assays developed here provide a novel, simple and efficient method for assaying the behaviour of expressed thin filament proteins.

Item Type: Article
Uncontrolled keywords: actin; Ca-regulation; skeletal muscle; cardiac muscle; cardiomyopathies
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Suzanne Duffy
Date Deposited: 19 Mar 2008 10:23
Last Modified: 20 May 2014 15:48
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