Hedgehog Interacting Protein (HHIP)

Hedgehog-interacting protein is a protein similar to the mouse hedgehog-interacting protein, a regulatory component of the Hedgehog signaling pathway. Members of the hedgehog family are evolutionarily conserved proteins which are involved in many fundamental processes in embryonic development. Hip cDNA encodes a type I transmembrane glycoprotein, which is expressed in all hedgehog target tissues and binds all 3 mammalian hedgehog proteins  with an affinity similar to that of the Ptc protein. Hip expression is upregulated in response to Hh signaling. Ectopic expression of Hip in transgenic mice results in severe skeletal defects similar to those observed in Indian hedgehog (IHH) mutants, demonstrating that Hip is involved in the attenuation of hedgehog signaling.