Phosphatidylinositol transfer protein

Pfam_box
Symbol = IP_trans
Name =

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width =220
caption = Phosphatidylinositol transfer protein, beta isoform
Pfam= PF02121
InterPro= IPR001666
SMART=
Prosite =
SCOP = 1fvz
TCDB =
OPM family= 147
OPM protein= 2a1l
PDB=PDB3|2a1lA:2-254 PDB3|1t27A:2-255 PDB3|1kcmA:2-255PDB3|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 membranescite journal |author=Liscovitch M, Cantley LC |title=Signal transduction and membrane traffic: the PITP/phosphoinositide connection |journal=Cell |volume=81 |issue=5 |pages=659–662 |year=1995 |pmid=7774006 |doi=10.1016/0092-8674(95)90525-1] .

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.

tructure and evolution

Along with the structurally unrelated Sec14p family (found inPfam|PF00650), this family can bind/exchange one molecule ofphosphatidylinositol (PI) or phosphatidylcholine (PC) and thusaids their transfer between different membranecompartments. There are three sub-families - all share anN-terminal PITP-like domain, whose sequence is highlyconserved. It is described as consisting of three regions. TheN-terminal region is thought to bind the lipid and contains twohelices and an eight-stranded, mostly antiparallel beta-sheet. Anintervening loop region, which is thought to play a role inprotein-protein interactions, separates this from the C-terminalregion, which exhibits the greatest sequence variation and may beinvolved in membrane binding. PITP alpha (UniProt|Q00169) has a16-fold greater affinity for PI than PC. Together with PITP beta(UniProt|P48739), it is expressed ubiquitously in all tissues [1] .

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)

References

Further reading

* [1] . The PITP family of phosphatidylinositol transfer proteins. Hsuan J, Cockcroft S; Genome Biol 2001;2:REVIEWS3011. PMID|11574064