Homo- and heterotetrameric architecture of the epithelial Ca2+ channels TRPV5 and TRPV6

AUTOR(ES)

Hoenderop, J.G.J.

FONTE

Oxford University Press

RESUMO

The molecular assembly of the epithelial Ca2+ 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 Cd2+ 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 Ca2+ channels that varied with respect to Ca2+-dependent inactivation, Ba2+ selectivity and pharmacological block. Thus, Ca2+-transporting epithelia co-expressing TRPV5 and TRPV6 can generate a pleiotropic set of functional heterotetrameric channels with different Ca2+ transport kinetics.

Documentos Relacionados

• Functional expression of the epithelial Ca2+ channels (TRPV5 and TRPV6) requires association of the S100A10–annexin 2 complex
• Renal Ca2+ wasting, hyperabsorption, and reduced bone thickness in mice lacking TRPV5
• Direct association of ligand-binding and pore domains in homo- and heterotetrameric inositol 1,4,5-trisphosphate receptors
• The A563T variation of the renal epithelial calcium channel TRPV5 among African Americans enhances calcium influx
• Parathyroid Hormone Activates TRPV5 via PKA-Dependent Phosphorylation