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Transient Receptor Potential channel, Vanilloid subfamily (TRPV), types 5 and 6 TRPV5 and TRPV6 (TRPV5/6) are two homologous members within the vanilloid subfamily of the transient receptor potential (TRP) family. TRPV5 and TRPV6 show only 30-40% homology with other members of the TRP family and have unique properties that differentiates them from other TRP channels. They mediate calcium uptake in epithelia and their expression is dramatically increased in numerous types of cancer. The structure of TRPV5/6 shows the typical topology features of all TRP family members, such as six transmembrane regions, a short hydrophobic stretch between transmembrane segments 5 and 6, which is predicted to form the Ca2+ pore, and large intracellular N- and C-terminal domains. The N-terminal domain of TRPV5/6 contains three ankyrin repeats. This structural element is present in several proteins and plays a role in protein-protein interactions. The N- and C-terminal tails of TRPV5/6 each contain an internal PDZ motif which can function as part of a molecular scaffold via interaction with PDZ-domain containing proteins. A major difference between the properties of TRPV5 and TRPV6 is in their tissue distribution: TRPV5 is predominantly expressed in the distal convoluted tubules (DCT) and connecting tubules (CNT) of the kidney, with limited expression in extrarenal tissues. In contrast, TRPV6 has a broader expression pattern such as expression in the intestine, kidney, placenta, epididymis, exocrine tissues, and a few other tissues.
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