CUED Publications database

Is titin a 'winding filament'? A new twist on muscle contraction.

Nishikawa, KC and Monroy, JA and Uyeno, TE and Yeo, SH and Pai, DK and Lindstedt, SL (2012) Is titin a 'winding filament'? A new twist on muscle contraction. Proc Biol Sci, 279. pp. 981-990.

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Abstract

Recent studies have demonstrated a role for the elastic protein titin in active muscle, but the mechanisms by which titin plays this role remain to be elucidated. In active muscle, Ca(2+)-binding has been shown to increase titin stiffness, but the observed increase is too small to explain the increased stiffness of parallel elastic elements upon muscle activation. We propose a 'winding filament' mechanism for titin's role in active muscle. First, we hypothesize that Ca(2+)-dependent binding of titin's N2A region to thin filaments increases titin stiffness by preventing low-force straightening of proximal immunoglobulin domains that occurs during passive stretch. This mechanism explains the difference in length dependence of force between skeletal myofibrils and cardiac myocytes. Second, we hypothesize that cross-bridges serve not only as motors that pull thin filaments towards the M-line, but also as rotors that wind titin on the thin filaments, storing elastic potential energy in PEVK during force development and active stretch. Energy stored during force development can be recovered during active shortening. The winding filament hypothesis accounts for force enhancement during stretch and force depression during shortening, and provides testable predictions that will encourage new directions for research on mechanisms of muscle contraction.

Item Type: Article
Uncontrolled Keywords: Actin Cytoskeleton Actins Calcium Connectin Models, Biological Muscle Contraction Muscle Proteins Muscle Tonus Protein Kinases Sarcomeres
Subjects: UNSPECIFIED
Divisions: Div F > Computational and Biological Learning
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:41
Last Modified: 24 Nov 2014 01:04
DOI: 10.1098/rspb.2011.1304