HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 4, 2613-2619, January 28, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/4/2613    most recent M408553200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shitaka, Y. Articles by Miki, M. Search for Related Content PubMed PubMed Citation Articles by Shitaka, Y. Articles by Miki, M. Social Bookmarking                      What's this?

The Rates of Switching Movement of Troponin T between Three States of Skeletal Muscle Thin Filaments Determined by Fluorescence Resonance Energy Transfer^*

Yuji Shitaka, Chieko Kimura, and Masao Miki

From the Department of Applied Chemistry and Biotechnology, Fukui University, 3-9-1 Bunkyo, Fukui 910-8507, Japan

Troponin (Tn) plays the key roles in the regulation of striated muscle contraction. Tn consists of three subunits (TnT, TnC, and TnI). In combination with the stopped-flow method, fluorescence resonance energy transfer between probes attached to Cys-60 or Cys-250 of TnT and Cys-374 of actin was measured to determine the rates of switching movement of the troponin tail domain (Cys-60) and of the TnT-TnI coiled-coil C terminus (Cys-250) between three states (relaxed, closed, and open) of the thin filament. When the free Ca²⁺ concentration was rapidly changed, these domains moved with rates of 450 and 85 s^–1 at pH 7.0 on Ca²⁺ up and down, respectively. When myosin subfragment 1 (S1) was dissociated from thin filaments by rapid mixing with ATP, these domains moved with a single rate constant of 400 s^–1 in the presence and absence of Ca²⁺. The light scattering measurements showed that ATP-induced S1 dissociation occurred with a rate constant >800 s^–1. When S1 was rapidly mixed with the thin filament, these domains moved with almost the same or slightly faster rates than those of S1 binding measured by light scattering. In most but not all aspects, the rates of movement of the troponin tail domain and of the TnT-TnI coiled-coil C terminus were very similar to those of certain TnI sites (N terminus, Cys-133, and C terminus) previously characterized (Shitaka, Y., Kimura, C., Iio, T., and Miki, M. (2004) Biochemistry 43, 10739–10747), suggesting that a series of conformational changes in the Tn complex during switching on or off process occurs synchronously.

Received for publication, July 28, 2004 , and in revised form, November 15, 2004.

^* This work was supported by the Special Coordination Funds of the Ministry of Education, Culture, Sports, Science, and Technology of the Japanese Government. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed. Tel.: 81-776-27-8786; Fax: 81-776-27-8747; E-mail: masao{at}acbio2.acbio.fukui-u.ac.jp.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?