Linked Life Data

17599911

Source:http://linkedlifedata.com/resource/pubmed/id/17599911

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
35
pubmed:dateCreated
2007-8-27
pubmed:abstractText
The channel kinases TRPM6 and TRPM7 have recently been discovered to play important roles in Mg2+ and Ca2+ homeostasis, which is critical to both human health and cell viability. However, the molecular basis underlying these channels' unique Mg2+ and Ca2+ permeability and pH sensitivity remains unknown. Here we have created a series of amino acid substitutions in the putative pore of TRPM7 to evaluate the origin of the permeability of the channel and its regulation by pH. Two mutants of TRPM7, E1047Q and E1052Q, produced dramatic changes in channel properties. The I-V relations of E1052Q and E1047Q were significantly different from WT TRPM7, with the inward currents of 8- and 12-fold larger than TRPM7, respectively. The binding affinity of Ca2+ and Mg2+ was decreased by 50- to 140-fold in E1052Q and E1047Q, respectively. Ca2+ and Mg2+ currents in E1052Q were 70% smaller than those of TRPM7. Strikingly, E1047Q largely abolished Ca2+ and Mg2+ permeation, rendering TRPM7 a monovalent selective channel. In addition, the ability of protons to potentiate inward currents was lost in E1047Q, indicating that E1047 is critical to Ca2+ and Mg2+ permeability of TRPM7, and its pH sensitivity. Mutation of the corresponding residues in the pore of TRPM6, E1024Q and E1029Q, produced nearly identical changes to the channel properties of TRPM6. Our results indicate that these two glutamates are key determinants of both channels' divalent selectivity and pH sensitivity. These findings reveal the molecular mechanisms underpinning physiological/pathological functions of TRPM6 and TRPM7, and will extend our understanding of the pore structures of TRPM channels.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
31
pubmed:volume
282
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
25817-30
pubmed:dateRevised
2011-10-19
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Molecular determinants of Mg2+ and Ca2+ permeability and pH sensitivity in TRPM6 and TRPM7.
pubmed:affiliation
Center for Cardiology and Cardiovascular Biology, Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural