Linked Life Data

19141619

Source:http://linkedlifedata.com/resource/pubmed/id/19141619

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2009-3-2
pubmed:abstractText
The crystal structures of the CBD1 and CBD2 domains of the Na+/Ca2+ exchanger protein (NCX1) provided a major breakthrough in Ca2+-dependent regulation of NCX1, although the dynamic aspects of the underlying molecular mechanisms are still not clear. Here we provide new experimental approaches for evaluating the kinetic and equilibrium properties of Ca2+ interaction with regulatory sites by using purified preparations of CBD1, CBD2, and CBD12 proteins. CBD12 binds approximately 6 Ca2+ ions (mol/mol), whereas the binding of only approximately 2 Ca2+ ions is observed (with a Hill coefficient of nH=approximately 2) either for CBD1 or CBD2. In the absence of Mg2+, CBD1 has a much higher affinity for Ca2+ (Kd=0.3+/-1.2 microm) than CBD2 (Kd=5.0+/-1.2 microm). The Ca2+ dissociation from CBD2 (koff=230+/-70 s(-1)) is at least 25 times faster than from CBD1 (koff=10+/-3 s(-1)), whereas the kon values indicate fast kinetics for Ca2+ binding (kon=koff/Kd=10(7)-10(8) m(-1) s(-1)) for both CBDs. At 2-5 mm Mg2+, both CBDs bind Ca2+, with a Kd of 1-2 microm (Mg2+ has very little effect on Ca2+ off rates). Mg2+ cannot occupy the primary site of CBD2, whereas the other Ca2+ sites of CBDs interact with Mg2+ as well. There is no competition between Na+ and Ca2+ for any CBD site. The kinetically diverse Ca2+ sensors may sense differentially the dynamic swings in [Ca2+] within specific subcellular compartments (dyadic cleft, submembrane space, bulk cytosol, etc.).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
284
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6185-93
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Kinetic and equilibrium properties of regulatory calcium sensors of NCX1 protein.
pubmed:affiliation
Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv 69978, Israel.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't