Nephrocystin -1 is a protein in the adherence compounds of the epithelial cells of vertebrates, which is probably responsible for the control of cell polarity. Thus, it is a structural protein that is associated with the primary cilium. In humans is Nephrocystin -1, especially in the pituitary, spinal cord, expression, thyroid, testis, skeletal muscle, lymph node, and bronchial tubes, but also in the heart, kidneys and pancreas. Mutations in the gene can NPHP1 to juvenile nephronophthisis, Senior - Loken syndrome type 1, or Joubert syndrome type lead 4.

Nephrocystin -1 binds to the cell migration protein CAS and supports signaling cascades that come about through tyrosine kinase 2beta ( PTK2B ) in the cellular matrix. Nephrocystin - 1 also binds to Nephroretinin and tensin, and it interacts with Inversin and nephrocystin -2, as well as with the Ack1 kinase.

In the nematode worm ( Caenorhabditis elegans) cause defects in nephrocystin -1 to behavioral problems that are typical for sensory defects at the cilia, such as reduced efficiency in the male copulation and defects in chemotaxis to volatile substances. Nephrocystin - 1 is localized at the base of the worm of the primary cilium.