Linked Life Data

9894007

Source:http://linkedlifedata.com/resource/pubmed/id/9894007

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1999-2-23
pubmed:abstractText
Thin filament regulation is mediated by the presence of tropomyosin (Tm) and troponin (Tn) on the actin filament. Binding of Tm alone induces two states, closed and open (with the equilibrium between them defined by KT), which differ in their affinity for myosin subfragment 1 (S1). Cooperative switching between the states results in characteristic sigmoidal myosin S1 binding curves. In the presence of Tn and absence of Ca2+, a third state, blocked, has previously been kinetically shown to be present, leading to the three state model of McKillop and Geeves [(1993) Biophys. J. 65, 693-701]. We have measured equilibrium binding of S1 to phalloidin-stabilized pyrene-actin filaments by monitoring the pyrene fluorescence at 50 nM, a concentration 10-fold lower than previously possible. In combination with kinetic studies, we show that the data can be fitted to a modified version of the three-state model with an additional term allowing for a varying apparent cooperative unit size (n). Our results show that the apparent cooperative unit size (n) is dependent upon both the presence of Tn and of Ca2+. Also in the absence of Ca2+, the occupancy of the blocked state (defined by KB) is accompanied by a 2-3-fold reduction in KT. These results are discussed in comparison to the Hill model [(1980) Proc. Natl. Acad. Sci. U.S.A. 77, 3186-3190] and a flexible model of thin filament regulation based upon that of Lehrer et al. [(1997) Biochemistry 36, 13449-13455].
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1102-10
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Cooperativity and switching within the three-state model of muscle regulation.
pubmed:affiliation
Max Planck Institut für Moleculare Physiologie, Dortmund, Germany.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.