Linked Life Data

15752712

Source:http://linkedlifedata.com/resource/pubmed/id/15752712

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2005-3-8
pubmed:abstractText
Ca(2+)-binding sites I and II in the N-terminal lobe of molluscan troponin C (TnC) have lost the ability to bind Ca(2+) due to substitutions of the amino acid residues responsible for Ca(2+) liganding. To evaluate the functional importance of the Ca(2+)-deficient N-terminal lobe in the Ca(2+)-regulatory function of molluscan troponin, we constructed chimeric TnCs comprising the N-terminal lobes from rabbit fast muscle and squid mantle muscle TnCs and the C-terminal lobe from akazara scallop TnC, TnC(RA), and TnC(SA), respectively. We characterized their biochemical properties as compared with those of akazara scallop wild-type TnC (TnC(AA)). According to equilibrium dialysis using (45)Ca(2+), TnC(RA), and TnC(SA) bound stoichiometrically 3 mol Ca(2+)/mol and 1 mol Ca(2+)/mol, respectively, as expected from their primary structures. All the chimeric TnCs exhibited difference-UV-absorption spectra at around 280-290 nm upon Ca(2+) binding and formed stable complexes with akazara scallop troponin I, even in the presence of 6M urea, if Ca(2+) was present. However, when the troponin complexes were constructed from chimeric TnCs and akazara scallop troponin T and troponin I, they showed different Ca(2+)-regulation abilities from each other depending on the TnC species. Thus, the troponin containing TnC(SA) conferred as high a Ca(2+) sensitivity to Mg-ATPase activity of rabbit actomyosin-akazara scallop tropomyosin as did the troponin containing TnC(AA), whereas the troponin containing TnC(RA) conferred virtually no Ca(2+) sensitivity. Our findings indicate that the N-terminal lobe of molluscan TnC plays important roles in molluscan troponin regulation, despite its inability to bind Ca(2+).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0003-9861
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
436
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
83-90
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Functional importance of Ca2+-deficient N-terminal lobe of molluscan troponin C in troponin regulation.
pubmed:affiliation
Laboratory of Biochemistry and Biotechnology, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't