Polycystin-1 (PC1), encoded by the Pkd1 gene, is a large transmembrane protein whose mutation is involved in autosomal dominant polycystic kidney disease. When expressed, PC1 activates a G-protein signaling pathway that subsequently modulates Ca(2+) channels. PC1 is highly expressed in developing tissue and via its C-terminus tail forms a complex with polycystin-2; this complex, found to be located at the primary cilia, seems to act as a mechanosensor that could affect proliferation, differentiation and apoptosis of cells. Also, loss of polycystins correlates with disruption of flow-dependent and steady-state intracellular Ca(2+) signaling. Despite the lack of clarity on the role of the polycystins as mechanosensor molecules, a new interest in this PCs/primary cilium complex is providing continuously new insights. In this review, some of the known features of PC1 such as structure, function, signaling pathways involved and its role as a possible therapeutic target are being discussed.
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