The PX domain is a phosphoinositide

Phosphatidylinositol

Phosphatidylinositol is a negatively charged phospholipid and a minor component in the cytosolic side of eukaryotic cell membranes....

-binding structural domain involved in targeting of proteins to cell membranes.

This domain was first found in P40phox and p47phox domains of NADPH oxidase

NADPH oxidase

The NADPH oxidase is a membrane-bound enzyme complex. It can be found in the plasma membrane as well as in the membrane of phagosome.-Subunits:It is made up of six subunits...

 (phox stands for phagocytic oxidase). It was also identified in many other proteins involved in membrane trafficking, including nexins, Phospholipase D

Phospholipase D

Phospholipase D is an enzyme which is located in the plasma membrane and catalyzes the hydrolysis of phosphatidylcholine to form phosphatidic acid , releasing the soluble choline headgroup into the cytosol...

, and phosphoinositide

Phosphatidylinositol

Phosphatidylinositol is a negatively charged phospholipid and a minor component in the cytosolic side of eukaryotic cell membranes....

-3-kinase

Kinase

In chemistry and biochemistry, a kinase is a type of enzyme that transfers phosphate groups from high-energy donor molecules, such as ATP, to specific substrates, a process referred to as phosphorylation. Kinases are part of the larger family of phosphotransferases...

s.

The PX domain is structurally conserved in eukaryote

Eukaryote

A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...

s, although amino acid sequences show little similarity. PX domains interact primarily with PtdIns(3)P

Phosphatidylinositol 3-phosphate

Phosphatidylinositol 3-phosphate is a phospholipid found in cell membranes that helps to recruit a range of proteins, many of which are involved in protein trafficking, to the membranes...

 lipids. However some of them bind to phosphatidic acid

Phosphatidate

Phosphatidic acids are the acid forms of phosphatidates, a part of common phospholipids, major constituents of cell membranes. Phosphatidic acids are the simplest diacyl-glycerophospholipids.-Structure:...

, PtdIns(3,4)P2

Phosphatidylinositol (3,4)-bisphosphate

Phosphatidylinositol -bisphosphate is a minor phospholipid component of cell membranes, yet an important second messenger...

, PtdIns(3,5)P2

Phosphatidylinositol (3,5)-bisphosphate

Phosphatidylinositol -bisphosphate is a minor phospholipid component of cell membranes, yet important in distinguishing cell compartments...

, PtdIns(4,5)P2

Phosphatidylinositol (4,5)-bisphosphate

Phosphatidylinositol 4,5-bisphosphate or PtdInsP2, also known simply as PIP2, is a minor phospholipid component of cell membranes...

, and PtdIns(3,4,5)P3

Phosphatidylinositol (3,4,5)-trisphosphate

Phosphatidylinositol -triphosphate , abbreviated PIP3, is the product of the class I phosphoinositide 3-kinases phosphorylation on phosphatidylinositol -bisphosphate .-Discovery:...

. The PX-domain can also interact with other domains and proteins.

Human proteins containing this domain

Sorting nexins contain this domain. Other examples include:

• HS1BP3
  HS1BP3
  HCLS1 binding protein 3 also known as HS1BP3 is a protein which in humans is encoded by the HS1BP3 gene.- Function :The protein encoded by this gene shares similarity with mouse Hs1bp3, an Hcls1-interacting protein that may be involved in lymphocyte activation.HS1BP3 binds members of the 14-3-3...
  
  
• KIF16B (SNX23)
• NCF1; NCF1C
  NCF1C
  Putative neutrophil cytosol factor 1C is a protein that in humans is encoded by the NCF1C gene.-Further reading:...
  
  ; NCF4
  Neutrophil cytosolic factor 4
  Neutrophil cytosol factor 4 is a protein that in humans is encoded by the NCF4 gene.-Interactions:Neutrophil cytosolic factor 4 has been shown to interact with Ku70, Neutrophil cytosolic factor 1 and Moesin.-Further reading:...
  
  ; NISCH
  NISCH
  Nischarin is a protein that in humans is encoded by the NISCH gene.-Further reading:...
  
  
• PIK3C2A
  PIK3C2A
  Phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing alpha polypeptide is an enzyme that in humans is encoded by the PIK3C2A gene.-Further reading:...
  
  ; PIK3C2B
  PIK3C2B
  Phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing beta polypeptide is an enzyme that in humans is encoded by the PIK3C2B gene.-Further reading:...
  
  ; PIK3C2G
  PIK3C2G
  Phosphatidylinositol-4-phosphate 3-kinase C2 domain-containing gamma polypeptide is an enzyme that in humans is encoded by the PIK3C2G gene.-Further reading:...
  
  ; PLD1
  Phospholipase D1
  Phospholipase D1 is an enzyme that in humans is encoded by the PLD1 gene.-Interactions:Phospholipase D1 has been shown to interact with RALA, BIN1, Amphiphysin, Alpha-synuclein, PEA15, RHOA, Protein kinase N1 and CDC42.-Inhibitors:...
  
  ; PLD2
  PLD2
  Phospholipase D2 is an enzyme that in humans is encoded by the PLD2 gene.-Interactions:PLD2 has been shown to interact with BIN1, Amphiphysin, Aldolase A, PLCG1, ARF1, Src, PRKCD, Glyceraldehyde 3-phosphate dehydrogenase ,Caveolin 1,and Wiskott-Aldrich syndrome protein.-Inhibitors:* N--2-naphthamide:...
  
  ; PXK
  PXK
  PX domain containing serine/threonine kinase also known as PXK is a protein which in humans is encoded by the PXK gene.- Function :...
  
  
• RPS6KC1
  RPS6KC1
  Ribosomal protein S6 kinase delta-1 is an enzyme that in humans is encoded by the RPS6KC1 gene.-Further reading:...
  
  
• SGK3
  SGK3
  Serine/threonine-protein kinase Sgk3 is an enzyme that in humans is encoded by the SGK3 gene.-Further reading:...
  
  ; SH3PXD2A
  SH3PXD2A
  SH3 and PX domain-containing protein 2A is a protein that in humans is encoded by the SH3PXD2A gene.-Further reading:...
  
  ; SNAG1
  SNAG1
  Sorting nexin-18 is a protein that in humans is encoded by the SNX18 gene.-Further reading:...