Linked Life Data

2716058

Source:http://linkedlifedata.com/resource/pubmed/id/2716058

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1989-6-19
pubmed:abstractText
Co-operative association, in which a protein subunit is held simultaneously by two bonds, is enormously more favorable than association forming either bond alone. A theoretical framework for calculating the effect of co-operativity is developed here, which should have a broad application to protein-protein and protein-DNA associations. The theory is applied in detail to actin. Fragmentation of an actin filament is extremely unfavorable: the association constant for annealing-fragmentation is estimated here to be at least 10(13) M-1. In contrast to these very strong bonds within the filament, subunits are loosely attached at the end, with an association constant of 2 x 10(5) M-1. The eight orders of magnitude difference between annealing-fragmentation and end association can be attributed to the co-operative formation of one additional protein-protein bond in the annealing reaction. This observation, and a quantitative analysis of the co-operativity, lead to an important conclusion: the longitudinal bond, which connects subunits in the long-pitch helix, must be substantially stronger than the diagonal bond, which connect subunits between these helices. This conclusion contradicts some recent models based on Fourier construction, in which the longitudinal bond is weak or absent. Prominent longitudinal bonds also require a rigidity of the actin filament that must be reconciled with previous reports of torsional flexibility. A hinge within the actin subunit is suggested, separating it into two flexibly attached domains. In one possible model the two domains are oriented radially: the inner domains are connected by longitudinal and diagonal bonds to form a relatively rigid helical backbone, and the outer domains are attached to this backbone by flexible hinges, permitting them to move through angles of 10 degrees to 20 degrees or more. Flexibility of the outer, myosin-binding domain should be functionally important, permitting attachment of myosin cross-bridges over a range of angles.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
206
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
465-74
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Co-operativity in protein-protein association. The structure and stability of the actin filament.
pubmed:affiliation
Department of Cell Biology, Duke University Medical Center, Durham, NC 27710.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.