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72 kDa inositol polyphosphate 5-phosphatase, also known as phosphatidylinositol-4,5-bisphosphate 5-phosphatase or Pharbin, is an enzyme that in humans is encoded by the INPP5E gene.[1][2]


INPP5E is a phosphatidyl inositol 3,4,5-trisphosphate (PtdInsP3) and phosphatidylinositol 4,5-bisphosphate 5-phosphatase. Its intracellular localzation is the primary cilium, a small organelle involved in signal transduction. INPP5E plays a role in hydrolizing PtdInsP3 produced in response to various growth factors such as PDGF. Inactivation of the mouse INPP5E gene decreases primary cilia stability, leading to a multiorgan disorder, including absence of eyes, polydactyly, exencephaly and renal cysts.

Clinical significance[edit]

Mutations in the INPP5E are associated with MORM syndrome[3] and Joubert syndrome.[4]


  1. ^ "Entrez Gene: inositol polyphosphate-5-phosphatase". 
  2. ^ Kisseleva MV, Wilson MP, Majerus PW (June 2000). "The isolation and characterization of a cDNA encoding phospholipid-specific inositol polyphosphate 5-phosphatase". J. Biol. Chem. 275 (26): 20110–6. doi:10.1074/jbc.M910119199. PMID 10764818. 
  3. ^ Hampshire, DJ; Ayub M; Springell K; Roberts E; Jafri H; Rashid Y; Bond J; Riley JH; Woods CG (2006). "MORM syndrome (mental retardation, truncal obesity, retinal dystrophy and micropenis), a new autosomal recessive disorder, links to 9q34". Eur J Hum Genet. 14 (5): 543–8. doi:10.1038/sj.ejhg.5201577. PMID 16493448. 
  4. ^ Bielas SL, Silhavy JL, Brancati F, et al. (September 2009). "Mutations in INPP5E, encoding inositol polyphosphate-5-phosphatase E, link phosphatidyl inositol signaling to the ciliopathies". Nat. Genet. 41 (9): 1032–6. doi:10.1038/ng.423. PMC 2746682Freely accessible. PMID 19668216. 

Further reading[edit]

This article incorporates text from the United States National Library of Medicine, which is in the public domain.