Linked Life Data

15933764

Source:http://linkedlifedata.com/resource/pubmed/id/15933764

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2005-7-1
pubmed:abstractText
The EF-hand Ca(2+)-binding protein calmyrin is expressed in many tissues and can interact with multiple effector proteins, probably as a sensor transferring Ca(2+) signals. As oligomerization may represent one of Ca(2+)-signal transduction mechanisms, we characterised recombinant calmyrin forms using non-reducing SDS/PAGE, analytical ultracentrifugation and gel filtration. We also aimed at identification of biologically active calmyrin forms. Non-reducing SDS/PAGE showed that in vitro apo- and Ca(2+)-bound calmyrin oligomerizes forming stable intermolecular disulfide bridges. Ultracentrifugation indicated that at a 220 microM initial protein concentration apo-calmyrin existed in an equilibrium of a 21.9 kDa monomer and a 43.8 kDa dimer (trimeric or tetrameric species were not detected). The dimerization constant was calculated as Ka = 1.78 x 103 M(-1) at 6 degrees C. Gel filtration of apo- and Ca(2+)-bound calmyrin at a 100 microM protein concentration confirmed an equilibrium of a monomer and a covalent dimer state. Importantly, both monomer and dimer underwent significant conformational changes in response to binding of Ca(2+). However, when calmyrin forms were analyzed under non-reducing conditions in cell extracts by Western blotting, only monomeric calmyrin was detected in human platelets and lymphocytes, and in rat brain. Moreover, in contrast to recombinant calmyrin, crosslinking did not preserve any dimeric species of calmyrin regardless of Ca(2+) concentrations. In summary, our data indicate that although calmyrin forms stable covalent dimers in vitro, it most probably functions as a monomer in vivo.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1734-154X
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
52
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
469-76
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Calcium-binding calmyrin forms stable covalent dimers in vitro, but in vivo is found in monomeric form.
pubmed:affiliation
Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't