Polycystin cation channel, PKD1/PKD2 (IPR013122)

Short name: PKD1_2_channel

Overlapping homologous superfamilies


Domain relationships



Polycystic kidney diseases (PKD) are disorders characterised by large numbers of cysts distributed throughout grossly-enlarged kidneys. Cyst development is associated with impairment of kidney function, and ultimately kidney failure and death [PMID: 8643665]. Most cases of autosomal dominant PKD result from mutations in the PKD1 gene that cause premature protein termination.

A second gene for autosomal dominant polycystic kidney disease has been identified by positional cloning [PMID: 8650545]. The predicted 968-amino acid sequence of the PKD2 gene product (polycystin-2) contains 6 transmembrane domains, with intracellular N- and C-termini. Polycystin-2 shares some similarity with the family of voltage-activated calcium (and sodium) channels, and contains a potential calcium-binding domain.

Polycystin-2 is strongly expressed in ovary, foetal and adult kidney, testis, and small intestine. Polycystin-1 requires the presence of this protein for stable expression and is believed to interact with it via its C terminus. All mutations between exons 1 and 11 result in a truncated polycystin-2 that lacks a calcium-binding EF-hand domain and the cytoplasmic domains required for the interaction of polycystin-2 with polycystin-1 [PMID: 9326320]. PKD2, although clinically milder than PKD1, has a deleterious impact on life expectancy.

This entry contains proteins belonging to the polycystin family including Mucolipin and Polycystin-1 and -2 (PKD1 and PKD2). The domain contains the cation channel region of PKD1 and PKD2 proteins. PKD1 and PKD2 may function through a common signalling pathway that is necessary for normal tubulogenesis. The PKD2 gene product has six transmembrane spans with intracellular amino- and carboxyl-termini [PMID: 8650545].

Mucolipin is a cationic channel which probably plays a role in the endocytic pathway and in the control of membrane trafficking of proteins and lipids. It could play a major role in the calcium ion transport regulating lysosomal exocytosis [PMID: 11013137, PMID: 12459486, PMID: 14749347].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.