Fig. 3.

Ca²⁺ transport proteins in the distal convoluted tubule (DCT) and connecting tubule (CNT). (a) The molecular structure of transient receptor potential vanilloid (TRPV) 5 and TRPV6. TRPV 5/6 consists of six transmembrane domains and ankyrin repeat at the N-terminal. The functional pore is composed with TM5 and TM6 of the tetramer2). (b) TRPV5 is exclusively expressed in the apical membrane of the DCT and CNT cells (especially DCT-2). TRPV6 is co-localized with TRPV5, but also observed in the collecting duct (the lower panel). Na⁺/Cl^- cotransporter (NCC) is the DCT and CNT marker10, 11). ECaC, epithelial calcilulm channel 1 (TRPV5); NCX, Na²⁺/Ca²⁺ exchanger; CaBP28K, calbindin-D_28K; AQP2, aquaporin 2.