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XB-ART-5778
EMBO J 2003 Feb 17;224:776-85. doi: 10.1093/emboj/cdg080.
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Homo- and heterotetrameric architecture of the epithelial Ca2+ channels TRPV5 and TRPV6.

Hoenderop JG , Voets T , Hoefs S , Weidema F , Prenen J , Nilius B , Bindels RJ .


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The molecular assembly of the epithelial Ca(2+) channels (TRPV5 and TRPV6) was investigated to determine the subunit stoichiometry and composition. Immunoblot analysis of Xenopus laevis oocytes expressing TRPV5 and TRPV6 revealed two specific bands of 75 and 85-100 kDa, corresponding to the core and glycosylated proteins, respectively, for each channel. Subsequently, membranes of these oocytes were sedimented on sucrose gradients. Immuno blotting revealed that TRPV5 and TRPV6 complexes migrate with a mol. wt of 400 kDa, in line with a tetrameric structure. The tetrameric stoichiometry was confirmed in an electrophysiological analysis of HEK293 cells co-expressing concatemeric channels together with a TRPV5 pore mutant that reduced Cd(2+) sensitivity and voltage-dependent gating. Immuno precipitations using membrane fractions from oocytes co-expressing TRPV5 and TRPV6 demonstrated that both channels can form heteromeric complexes. Expression of all possible heterotetrameric TRPV5/6 complexes in HEK293 cells resulted in Ca(2+) channels that varied with respect to Ca(2+)-dependent inactivation, Ba(2+) selectivity and pharmacological block. Thus, Ca(2+)-transporting epithelia co-expressing TRPV5 and TRPV6 can generate a pleiotropic set of functional heterotetrameric channels with different Ca(2+) transport kinetics.

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Species referenced: Xenopus laevis
Genes referenced: trpv5 trpv6

References [+] :
Bähner, The visual G protein of fly photoreceptors interacts with the PDZ domain assembled INAD signaling complex via direct binding of activated Galpha(q) to phospholipase cbeta. 2000, Pubmed