| The troponin I: inhibitory peptide uncouples force generation and the cooperativity of contractile activation in mammalian skeletal muscle. | |
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MedLine Citation:
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PMID: 23340900 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Hodges and his colleagues identified a 12 amino acid fragment of troponin I (TnI-ip) that inhibits Ca(2+)-activated force and reduces the effectiveness Ca(2+) as an activator. To understand the role of troponin C (TnC) in the extended cooperative interactions of thin filament activation, we compared the effect of TnI-ip with that of partial troponin TnC extraction. Both methods reduce maximal Ca(2+)-activated force and increase [Ca(2+)] required for activation. In contrast to TnC extraction, TnI-ip does not reduce the extended cooperative interactions between adjacent thin filament regulatory units as assessed by the slope of the pCa/force relationship. Additional evidence that TnI-ip does not interfere with extended cooperativity comes from studies that activate muscle by rigor crossbridges (RXBs). TnI-ip increases both the cooperativity of activation and the concentration of RXBs needed for maximal force. This shows that TnI-ip binding to TnC increases the stability of the relaxed state of the thin filament. TnI-ip, therefore, uncouples force generation from extended cooperativity in both Ca(2+) and RXB activated muscle contraction. Because maximum force can be reduced with no change-or even an increase-in cooperativity, force-generating crossbridges do not appear to be the primary activators of cooperativity between thin filament regulatory units of skeletal muscle. |
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Authors:
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Fred Schachat; Philip W Brandt |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2013-1-23 |
Journal Detail:
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Title: Journal of muscle research and cell motility Volume: - ISSN: 1573-2657 ISO Abbreviation: J. Muscle Res. Cell. Motil. Publication Date: 2013 Jan |
Date Detail:
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Created Date: 2013-1-23 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8006298 Medline TA: J Muscle Res Cell Motil Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Division of Physiology, Department of Cell Biology, Duke University Medical School, Box 3011, Durham, NC, 27710, USA, f.schachat@cellbio.duke.edu. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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