Forms a nonselective cation channel (PubMed:11854751, PubMed:11991947, PubMed:15692563, PubMed:26269590, PubMed:27071085, PubMed:31441214, PubMed:39009345). Can function as a homotetrameric ion channel or can form heteromer with PKD1 (PubMed:31441214, PubMed:33164752). Displays distinct function depending on its subcellular localization and regulation by its binding partners (PubMed:11854751, PubMed:11991947, PubMed:27214281, PubMed:29899465). In primary cilium functions as a cation channel, with a preference for monovalent cations over divalent cations that allows K(+), Na(+) and Ca(2+) influx, with low selectivity for Ca(2+) (PubMed:27071085). Involved in fluid-flow mechanosensation by the primary cilium in renal epithelium (By similarity). In the endoplasmic reticulum, likely functions as a K(+) channel to facilitate Ca(2+) release (By similarity). The heterotetrameric PKD1/PKD2 channel has higher Ca(2+) permeability than homomeric PKD2 channel and acts as a primarily Ca(2+)-permeable channel (PubMed:31441214). Interacts with and acts as a regulator of a number of other channels, such as TRPV4, TRPC1, IP3R, RYR2, ultimately further affecting intracellular signaling, to modulate intracellular Ca(2+) signaling (PubMed:11854751, PubMed:11991947, PubMed:27214281, PubMed:29899465). Together with TRPV4, forms mechano- and thermosensitive channels in cilium (PubMed:18695040). In cardiomyocytes, PKD2 modulates Ca(2+) release from stimulated RYR2 receptors through direct association (By similarity). Also 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 (By similarity). Acts as a regulator of cilium length together with PKD1 (By similarity). Mediates systemic blood pressure and contributes to the myogenic response in cerebral arteries though vasoconstriction (By similarity). {ECO:0000250|UniProtKB:O35245, ECO:0000269|PubMed:11854751, ECO:0000269|PubMed:11991947, ECO:0000269|PubMed:15692563, ECO:0000269|PubMed:18695040, ECO:0000269|PubMed:26269590, ECO:0000269|PubMed:27071085, ECO:0000269|PubMed:27214281, ECO:0000269|PubMed:29899465, ECO:0000269|PubMed:31441214, ECO:0000269|PubMed:33164752, ECO:0000269|PubMed:39009345}. This is the function of PKD2 (polycystin 2, transient receptor potential cation channel, ENSG00000118762).