Nephrocystin 5 (NPHP5)

IQCB1 encodes a nephrocystin protein that interacts with calmodulin and the retinitis pigmentosa GTPase regulator protein. The encoded protein has a central coiled-coil region and two calmodulin-binding IQ domains. It is localized to the primary cilia of renal epithelial cells and connecting cilia of photoreceptor cells. The protein is thought to play a role in ciliary function. Defects in this gene result in Senior-Loken syndrome type 5. Alternative splicing results in multiple transcript variants. The deduced 598-amino acid protein contains a tyrosine phosphorylation site. Northern blot analysis detected high IQCB1 expression in lung and testis, intermediate expression in brain, skeletal muscle, and kidney, and low expression in placenta, liver, spleen, thymus, prostate, ovary, small intestine, colon, and peripheral blood leukocytes.