INPP5E

Description

The INPP5E (inositol polyphosphate-5-phosphatase E) is a protein-coding gene located on chromosome 9.

The INPP5E gene encodes for the 72 kDa inositol polyphosphate 5-phosphatase enzyme, also known as phosphatidylinositol-4,5-bisphosphate 5-phosphatase or Pharbin. This enzyme is involved in the hydrolysis of PtdInsP3, a molecule produced in response to growth factors like PDGF. INPP5E is localized within the primary cilium, a small organelle that plays a role in signal transduction. Mutations in the INPP5E gene are associated with MORM syndrome and Joubert syndrome. In mice, inactivation of the INPP5E gene leads to decreased primary cilia stability and multiorgan disorders including the absence of eyes, polydactyly, exencephaly, and renal cysts.

INPP5E is a phosphatidylinositol (PtdIns) phosphatase that specifically hydrolyzes the 5-phosphate of phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3), phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2). It is specific for lipid substrates and inactive towards water soluble inositol phosphates. INPP5E plays an essential role in the primary cilium by controlling ciliary growth and phosphoinositide 3-kinase (PI3K) signaling and stability.

INPP5E is also known as CORS1, CPD4, JBTS1, MORMS, PPI5PIV, pharbin.

Associated Diseases

• Mental retardation, truncal obesity, retinal dystrophy, and micropenis syndrome
• Joubert syndrome 1
• Joubert syndrome with hepatic defect
• MORM syndrome
• Joubert syndrome
• Joubert syndrome with ocular defect