Linked Life Data

16005017

Source:http://linkedlifedata.com/resource/pubmed/id/16005017

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2005-10-24
pubmed:abstractText
The first human cardiac troponin I (hcTnI) mutation in the N-terminal 32 residue region, R21C (arginine residue number 21 mutated to cysteine), which has been linked to hypertrophic cardiomyopathy (HCM), has recently been reported. The effect of this mutation on the physiological function of hcTnI was investigated. Human cTnI R21C (in the absence or presence of troponin T and troponin C) was phosphorylated by protein kinase A (PKA) at a significantly slower rate than wild-type hcTnI. In skinned fiber studies, the TnI R21C mutant showed a large increase in Ca(2+)-sensitivity of force development when compared to wild-type TnI (DeltapCa(50)=0.33). Phosphorylation of skinned fibers containing TnI R21C by PKA resulted in a significantly smaller decrease in the Ca(2+)-sensitivity of force development when compared to phosphorylation of fibers containing wild-type TnI. The decreased sensitivity of TnI R21C to PKA is most likely due to a decreased ability of PKA to phosphorylate this TnI rather than conformational problems within this TnI. In addition, skinned fibers were found to contain an endogenous kinase that is capable of phosphorylating wild-type TnI. However, the endogenous kinase activity did not affect the Ca(2+)-sensitivity of force development, the Hill coefficient or maximal force of these skinned fibers. Actomyosin ATPase assays showed that the R21C mutation did not affect the inhibitory properties of TnI or the maximal ATPase activity. TnI R21C was also found to be more susceptible to proteolysis by calpain II than wild-type TnI. These results suggest that this R21C mutation in TnI affects the Ca(2+)-sensitizing effect of Tn, the ability of TnI to be readily phosphorylated by PKA and the stability of TnI to calpain. The results also suggest that the N-terminal region may have important roles such as modulating the Ca(2+)-sensitivity of force-development.
pubmed:grant
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0022-2828
pubmed:author
pubmed:issnType
Print
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
754-65
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
A mutation in the N-terminus of troponin I that is associated with hypertrophic cardiomyopathy affects the Ca(2+)-sensitivity, phosphorylation kinetics and proteolytic susceptibility of troponin.
pubmed:affiliation
Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, 1600 N.W. 10th Avenue, Miami, FL 33136, USA.
pubmed:publicationType
Journal Article, In Vitro, Research Support, N.I.H., Extramural