1.A.5.2.2
Polycystic kidney disease Z-like protein, TrpP3 or PKD2L1 (50% identical to Polycystin 2 (1.A.5.2.1); regulated by α-actinin (AAC17470) by direct binding; Li et al, 2007). May form a heterodimeric complex with PKD1L3 (1.A.5.1.2) to form the TRP sour taste channel receptor (Ishimaru et al., 2006; Ishimaru et al. 2010).  Polycystic kidney disease (PKD) protein 2 Like 1 (PKD2L1) is also called transient receptor potential polycystin-3 (TRPP3).  It regulates Ca²⁺-dependent hedgehog signalling in primary cilia, intestinal development and sour taste. Two intra-membrane residues, aspartic acid 349 (D349) and glutamic acid 356 (E356) in the third TMS are critical for PKD2L1 channel function which may itself sense acids (Hussein et al. 2015). Extracellular loops are involved in assemby of the complex (Salehi-Najafabadi et al. 2017). It Component of a heteromeric calcium-permeable ion channel formed by PKD1 and PKD2 that is activated by interaction between PKD1 and a Wnt family member, such as WNT3A and WNT9B. Can also form a functional, homotetrameric ion channel (PubMed:27214281). It functions as a cation channel involved in fluid-flow mechanosensation by the primary cilium in the renal epithelium (Nauli et al. 2003). It functions as outward-rectifying K⁺ channel, but is also permeable to Ca²⁺, and to a much lesser degree, to Na⁺ (Kleene and Kleene 2017). It
may contribute to the release of Ca²⁺ stores from the endoplasmic reticulum. Together with TRPV4, it forms mechano- and thermosensitive channels in cilia (Köttgen et al. 2008). The
PKD1 channel protein.  It is involved in left-right axis specification via its role in sensing nodal flow; forms a complex with PKD1L1 in cilia to facilitate flow detection in left-right patterning (Yoshiba et al. 2012 ; Katoh et al. 2023). Detection of asymmetric nodal flow gives rise to a Ca²⁺ signal that is required for normal, asymmetric expression of genes involved in the specification of body left-right laterality (Yoshiba et al. 2012).