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 (PubMed:27214281). Both PKD1 and PKD2 are required for channel activity (PubMed:27214281). Involved in renal tubulogenesis (PubMed:12482949). Involved in fluid-flow mechanosensation by the primary cilium in renal epithelium (By similarity). Acts as a regulator of cilium length, together with PKD2 (By similarity). The dynamic control of cilium length is essential in the regulation of mechanotransductive signaling (By similarity). The cilium length response creates a negative feedback loop whereby fluid shear-mediated deflection of the primary cilium, which decreases intracellular cAMP, leads to cilium shortening and thus decreases flow-induced signaling (By similarity). May be an ion-channel regulator. Involved in adhesive protein-protein and protein-carbohydrate interactions. Interacts with PKD2; the interaction is required for ciliary localization (PubMed:20881056). Component of a heterotetrameric channel complex with PKD2; the tetramer contains one PKD1 chain and three PKD2 chains (PubMed:30093605). Interacts with PKD2L1 (By similarity). Interacts with PRKX; involved in differentiation and controlled morphogenesis of the kidney (PubMed:17980165). Interacts (via extracellular domain) with WNT3A, WNT4, WNT5A and WNT9B (PubMed:27214281). Interacts with DVL1 and DVL2 (PubMed:27214281). Interacts with NPHP1 (via SH3 domain) (PubMed:20856870). Interacts with BBS1, BBS4, BBS5 and TTC8 (PubMed:24939912). Interacts with RGS7 (PubMed:10339594). PKD1 localization to the plasma and ciliary membranes requires PKD2, is independent of PKD2 channel activity, and involves stimulation of PKD1 autoproteolytic cleavage at the GPS domain. PKD1:PKD2 interaction is required to reach the Golgi apparatus from endoplasmic reticulum and then traffic to the cilia (By similarity). Ciliary localization of PKD1 requires BBS1 and ARL6/BBS3 (By similarity). Cell surface localization requires GANAB (PubMed:27259053). The LDL-receptor class A domain is atypical; the potential calcium-binding site is missing. After synthesis, undergoes cleavage between Leu-3048 and Thr-3049 in the GPS domain. Cleavage at the GPS domain occurs through a cis-autoproteolytic mechanism involving an ester-intermediate via N-O acyl rearrangement. This process takes place in the early secretory pathway, depends on initial N-glycosylation, and requires the REJ domain. There is evidence that cleavage at GPS domain is incomplete. Uncleaved and cleaved products may have different functions in vivo. The disease is caused by variants affecting the gene represented in this entry. Belongs to the polycystin family. Variant Cys-2379 has been originally described as a benign polymorphism (PubMed:10854095). However, it is a likely pathogenic mutation (PubMed:22508176). Polycystin-1