Polycystin expression in the kidney and other tissues: complexity, consensus and controversy

PKD1, the major gene mutated in autosomal dominant polycystic kidney disease, was identified in 1994, and fully sequenced in 1995. The protein which it encodes, polycystin-1, is the first member of a new family of proteins, whose functions presently remain unclear. This review seeks to highlight the difficulties researchers studying polycystin-1 have faced and to summarize the current areas of consensus and controversy between different groups, particularly with regard to the expression pattern, subcellular location and biochemical characterization of polycystin-1. Where relevant, more recent data regarding polycystin-2, the protein encoded by PKD2, will also be discussed.