A PDZ domain-containing protein with homology to Diphor-1 maps to human chromosome 1q21

The novel gene, Diphor-1, was recently cloned from rat kidney and shown to increase phosphate uptake in cells when co-expressed with a Na+-P-i cotrans porter, indicating that it may play a substantial role in cellular phosphat e balance. Previously, the phosphate wasting disorder, autosomal dominant h ypophosphatemic rickets (ADHR) was mapped to chromosome 12p13 by linkage an alysis. In the present work, PDZK1, a PDZ domain-containing protein highly homologous to rat Diphor-1, was shown to be expressed in human kidney. Base d upon its sequence similarity to rat Diphor-1, we considered PDZK1 a feasi ble candidate gene for ADHR. PDZK1 was found to localize to human chromosom e 1q21, thereby ruling it out as a candidate for ADHR.