Phosphatidylinositol transfer protein

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Phosphatidylinositol transfer protein, beta isoform
Identifiers
Symbol IP_trans
Pfam PF02121
InterPro IPR001666
SCOP 1fvz
OPM family 147
OPM protein 2a1l
Available PDB structures:

2a1lA:2-254 1t27A:2-255 1kcmA:2-255 1uw5C:2-254


Phosphatidylinositol transfer protein (PITP) is a ubiquitous cytosolic domain involved in transport of phospholipids from their site of synthesis in the endoplasmic reticulum and Golgi to other cell membranes[1].

Contents

[edit] Biological function

PITP has been also shown to be an essential component of the polyphosphoinositide synthesis machinery and is hence required for proper signalling by epidermal growth factor and f-Met-Leu-Phe, as well as for exocytosis. The role of PITP in polyphosphoinositide synthesis may also explain its involvement in intracellular vesicular traffic[1].

[edit] Structure and evolution

Along with the structurally unrelated Sec14p family (found in Pfam PF00650), this family can bind/exchange one molecule of phosphatidylinositol (PI) or phosphatidylcholine (PC) and thus aids their transfer between different membrane compartments. There are three sub-families - all share an N-terminal PITP-like domain, whose sequence is highly conserved. It is described as consisting of three regions. The N-terminal region is thought to bind the lipid and contains two helices and an eight-stranded, mostly antiparallel beta-sheet. An intervening loop region, which is thought to play a role in protein-protein interactions, separates this from the C-terminal region, which exhibits the greatest sequence variation and may be involved in membrane binding. PITP alpha (UniProt Q00169) has a 16-fold greater affinity for PI than PC. Together with PITP beta (UniProt P48739), it is expressed ubiquitously in all tissues [1].

[edit] Human proteins

The family of human phosphatidylinositol transfer proteins has several members:

  • Phosphatidylinositol transfer protein, alpha (PITPNA)
  • Phosphatidylinositol transfer protein, beta (PITPNB)
  • Phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC)
  • Phosphatidylinositol transfer protein, membrane-associated 1 (PITPNM1)
  • Phosphatidylinositol transfer protein, membrane-associated 2 (PITPNM2)
  • PITPNM family member 3 (PITPNM3)

[edit] References

  1. ^ a b Liscovitch M, Cantley LC (1995). "Signal transduction and membrane traffic: the PITP/phosphoinositide connection". Cell 81 (5): 659–662. doi:10.1016/0092-8674(95)90525-1. PMID 7774006. 

[edit] Further reading

  • [1]. The PITP family of phosphatidylinositol transfer proteins. Hsuan J, Cockcroft S; Genome Biol 2001;2:REVIEWS3011. PubMed
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This article includes text from the public domain Pfam and InterPro IPR001666