Identification ofPKD2L,a HumanPKD2-Related Gene: Tissue-Specific Expression and Mapping to Chromosome 10q25

Mutations inPKD2cause autosomal dominant kidney disease (ADPKD). Polycystin-2, thePKD2gene product, is an integral membrane glycoprotein of unknown function. We have identifiedPKD2L, another member of thePKD2gene family.PKD2Lis expressed in adult heart and skeletal muscle, brain, spleen, testis, and retina, and alternative transcripts of 2.4, 2.7, and 3.0 kb are seen. PKD2L shows 56% identity and 76% similarity with polycystin-2 over a 581-amino-acid span; however, the COOH-terminal 65 residues of PKD2L are unrelated to PKD2.PKD2Lis localized to chromosome 10q25 and is excluded as a candidate gene for autosomal recessive polycystic kidney disease, autosomal dominant polycystic liver disease, and the third form of ADPKD. Given the high degree of homology between PKD2L and PKD2, it is likely that the respective functions of these proteins are also closely related.