PC1 is a membrane-bound protein 4303 amino acids in length expressed largely upon the primary cilium, as well as apical membranes, adherens junctions, and desmosomes ^[4]. It possesses eleven transmembrane domains, a large extracellular N-terminal domain, and a short (~200 amino acid) cytoplasmic C-terminal domain ^[4][5]. This intracellular domain contains a coiled-coil domain through which PC1 interacts with polycystin 2 (PC2), a membrane-bound Ca²⁺-permeable ion channel.

PC1 has been proposed to act as a G protein–coupled receptor ^[4][6]. The C-terminal domain may be cleaved in a number of different ways. In one instance, a ~35 kDa portion of the tail has been found to accumulate in the cell nucleus in response to decreased fluid flow in the mouse kidney ^[7]. In another instance, a 15 kDa fragment may be yielded, interacting with transcriptional activator and co-activator STAT6 and p100, or components of the canonical Wnt signaling pathway in an inhibitory manner ^[8][9].

Evidence suggests that PC1 mediates mechanosensation of fluid flow by the primary cilium in the renal epithelium and of mechanical deformation of articular cartilage ^[10].

Splice variants encoding different isoforms have been noted for PKD1. The gene is closely linked to six pseudogenes in a known duplicated region on chromosome 16p.^[11]

• GeneReviews/NIH/NCBI/UW entry on Polycystic Kidney Disease, Autosomal Dominant