Functional expression of the epithelial Ca2+ channels (TRPV5 and TRPV6) requires association of the S100A10-annexin 2 complex

• Published in: The EMBO journal 2003-04, Vol.22 (7), p.1478-1487
• Main Authors: van de Graaf, Stan F.J., Hoenderop, Joost G.J., Gkika, Dimitra, Lamers, Dennis, Prenen, Jean, Rescher, Ursula, Gerke, Volker, Staub, Olivier, Nilius, Bernd, Bindels, René J.M.
• Format: Article
• Language: English
• Subjects: Amino acids; CaT1; ECaC; EMBO20; Life Sciences; p11; PDZ motif; siRNA; Yeasts
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.1093/emboj/cdg162

TRPV5 and TRPV6 constitute the Ca 2+ influx pathway in a variety of epithelial cells. Here, we identified S100A10 as the first auxiliary protein of these epithelial Ca 2+ channels using yeast two‐hybrid and GST pull‐down assays. This S100 protein forms a heterotetrameric complex with annexin 2 and associates specifically with the conserved sequence VATTV located in the C‐terminal tail of TRPV5 and TRPV6. Of these five amino acids, the first threonine plays a crucial role since the corresponding mutants (TRPV5 T599A and TRPV6 T600A) exhibited a diminished capacity to bind S100A10, were redistributed to a subplasma membrane area and did not display channel activity. Using GST pull‐down and co‐immunoprecipitation assays we demonstrated that annexin 2 is part of the TRPV5–S100A10 complex. Furthermore, the S100A10–annexin 2 pair colocalizes with the Ca 2+ channels in TRPV5‐expressing renal tubules and TRPV6‐expressing duodenal cells. Importantly, downregulation of annexin 2 using annexin 2‐specific small interfering RNA inhibited TRPV5 and TRPV6‐mediated currents in transfected HEK293 cells. In conclusion, the S100A10–annexin 2 complex plays a crucial role in routing of TRPV5 and TRPV6 to plasma membrane.