The Phox Homology domain, a phosphoinositide binding module; The PX domain is a phosphoinositide (PI) binding module involved in targeting proteins to membranes. Proteins containing PX domains interact with PIs and have been implicated in highly diverse functions such as cell signaling, vesicular trafficking, protein sorting, lipid modification, cell polarity and division, activation of T and B cells, and cell survival. Many members of this superfamily bind phosphatidylinositol-3-phosphate (PI3P) but in some cases, other PIs such as PI4P or PI(3,4)P2, among others, are the preferred substrates. In addition to protein-lipid interaction, the PX domain may also be involved in protein-protein interaction, as in the cases of p40phox, p47phox, and some sorting nexins (SNXs). The PX domain is conserved from yeast to humans and is found in more than 100 proteins. The majority of PX domain-containing proteins are SNXs, which play important roles in endosomal sorting.

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gi 665505963  28 FLEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 86
Cdd:cd07293    1 FLEIDVTNPQTVGVGRGRFTTYEIRLKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 59

The phosphoinositide binding Phox Homology domain of Sorting Nexin 3; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. SNX3 associates with early endosomes through a PX domain-mediated interaction with phosphatidylinositol-3-phosphate (PI3P). It associates with the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi, and functions as a cargo-specific adaptor for the retromer. SNX3 is required for the formation of multivesicular bodies, which function as transport intermediates to late endosomes. It also promotes cell surface expression of the amiloride-sensitive epithelial Na+ channel (ENaC), which is critical in sodium homeostasis and maintenance of extracellular fluid volume.

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                 ....*....|....*....|....*....|....*....|....*....|....*....
gi 665505963  28 FLEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 86
Cdd:cd07293    1 FLEIDVTNPQTVGVGRGRFTTYEIRLKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 59

PhoX homologous domain, present in p47phox and p40phox; Eukaryotic domain of unknown function present in phox proteins, PLD isoforms, a PI3K isoform.

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                   ....*....|....*....|....*....|....*....|....*....|....*.
gi 665505963    33 VSNPQTVGVGRGRFTTYEIRVKTNLpifklKESTVRRRYSDFEWLRSELERESKGR 88
Cdd:smart00312   1 VVEPEKIGDGKHYYYVIEIETKTGL-----EEWTVSRRYSDFLELHSKLKKHFPRS 51

The phosphoinositide binding Phox Homology domain of Sorting Nexin 3; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. SNX3 associates with early endosomes through a PX domain-mediated interaction with phosphatidylinositol-3-phosphate (PI3P). It associates with the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi, and functions as a cargo-specific adaptor for the retromer. SNX3 is required for the formation of multivesicular bodies, which function as transport intermediates to late endosomes. It also promotes cell surface expression of the amiloride-sensitive epithelial Na+ channel (ENaC), which is critical in sodium homeostasis and maintenance of extracellular fluid volume.

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gi 665505963  28 FLEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 86
Cdd:cd07293    1 FLEIDVTNPQTVGVGRGRFTTYEIRLKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 59

The phosphoinositide binding Phox Homology domain of Sorting Nexin 12; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. Some SNXs are localized in early endosome structures such as clathrin-coated pits, while others are located in late structures of the endocytic pathway. The specific function of SNX12 has yet to be elucidated.

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                 ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 665505963  26 SNFLEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESK 86
Cdd:cd07294    1 SNFLEIDIFNPQTVGVGRNRFTTYEVRMRTNLPIFKLKESCVRRRYSDFEWLKNELERDSK 61

The phosphoinositide binding Phox Homology domain of Sorting Nexins 1 and 2; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. This subfamily consists of SNX1, SNX2, and similar proteins. They harbor a Bin/Amphiphysin/Rvs (BAR) domain, which detects membrane curvature, C-terminal to the PX domain. Both domains have been shown to determine the specific membrane-targeting of SNX1. SNX1 and SNX2 are components of the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi. The retromer consists of a cargo-recognition subcomplex and a subcomplex formed by a dimer of sorting nexins (SNX1 and/or SNX2), which ensures effcient cargo sorting by facilitating proper membrane localization of the cargo-recognition subcomplex.

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gi 665505963  29 LEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESKGR 88
Cdd:cd06859    1 FEISVTDPVKVGDGMSAYVVYRVTTKTNLPDFKKSEFSVLRRYSDFLWLYERLVEKYPGR 60

Phox homology (PX) domain protein [Intracellular trafficking and secretion / General function prediction only];

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gi 665505963   9 RRLITKPqNLNDAYGPPSNFLEIDVSNPQTVGVG---RGRFTTYEIRVKTNLPIFKLKES---TVRRRYSDFEWLRSELE 82
Cdd:COG5391  112 LPTSLQP-PLSTSHTILDYFISSTVSNPQSLTLLvdsRDKHTSYEIITVTNLPSFQLRESrplVVRRRYSDFESLHSILI 190

                 ..
gi 665505963  83 RE 84
Cdd:COG5391  191 KL 192

The phosphoinositide binding Phox Homology domain of yeast sorting nexin Vps5p; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. Vsp5p is the yeast counterpart of human SNX1 and is part of the retromer complex, which functions in the endosome-to-Golgi retrieval of vacuolar protein sorting receptor Vps10p, the Golgi-resident membrane protein A-ALP, and endopeptidase Kex2. The PX domain of Vps5p binds phosphatidylinositol-3-phosphate (PI3P). Similar to SNX1, Vps5p contains a Bin/Amphiphysin/Rvs (BAR) domain, which detects membrane curvature, C-terminal to the PX domain. Both domains have been shown to determine the specific membrane-targeting of SNX1.

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gi 665505963  29 LEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELERESKGR 88
Cdd:cd06861    1 FEITVGDPHKVGDLTSAHTVYTVRTRTTSPNFEVSSFSVLRRYRDFRWLYRQLQNNHPGV 60

The phosphoinositide binding Phox Homology domain of Sorting Nexin 2; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. SNX2 is a component of the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi. The retromer consists of a cargo-recognition subcomplex and a subcomplex formed by a dimer of sorting nexins (SNX1 and/or SNX2), which ensures efficient cargo sorting by facilitating proper membrane localization of the cargo-recognition subcomplex. Similar to SNX1, SNX2 contains a Bin/Amphiphysin/Rvs (BAR) domain, which detects membrane curvature, C-terminal to the PX domain. The PX domain of SNX2 preferentially binds phosphatidylinositol-3-phosphate (PI3P), but not PI(3,4,5)P3. Studies on mice deficient with SNX1 and/or SNX2 suggest that they provide an essential function in embryogenesis and are functionally redundant.

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gi 665505963  29 LEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSEL 81
Cdd:cd07282    1 IEIGVSDPEKVGDGMNAYMAYRVTTKTSLSMFSRSEFSVRRRFSDFLGLHSKL 53

The phosphoinositide binding Phox Homology domain of Sorting Nexin 1; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. SNX1 is both membrane associated and a cytosolic protein that exists as a tetramer in protein complexes. It can associate reversibly with membranes of the endosomal compartment, thereby coating these vesicles. SNX1 is a component of the retromer complex, a membrane coat multimeric complex required for endosomal retrieval of lysosomal hydrolase receptors to the Golgi. The retromer consists of a cargo-recognition subcomplex and a subcomplex formed by a dimer of sorting nexins (SNX1 and/or SNX2), which ensures efficient cargo sorting by facilitating proper membrane localization of the cargo-recognition subcomplex. SNX1 contains a Bin/Amphiphysin/Rvs (BAR) domain C-terminal to the PX domain. The PX domain of SNX1 specifically binds phosphatidylinositol-3-phosphate (PI3P) and PI(3,5)P2, while the BAR domain detects membrane curvature. Both domains help determine the specific membrane-targeting of SNX1, which is localized to a microdomain in early endosomes where it regulates cation-independent mannose-6-phosphate receptor retrieval to the trans Golgi network.

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gi 665505963  29 LEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSEL-ERESK 86
Cdd:cd07281    1 LKVSITDPEKIGDGMNAYVVYKVTTQTSLLMFRSKHFTVKRRFSDFLGLYEKLsEKHSQ 59

PX domain; PX domains bind to phosphoinositides.

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gi 665505963   57 LPIFKLKESTVRRRYSDFEWLRSELERESKGR 88
Cdd:pfam00787   1 LPTFSLEEWSVRRRYSDFVELHKKLLRKFPSV 32

The phosphoinositide binding Phox Homology domain of Sorting Nexin 30; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. Some SNXs are localized in early endosome structures such as clathrin-coated pits, while others are located in late structures of the endocytic pathway. SNX30 harbors a Bin/Amphiphysin/Rvs (BAR) domain, which detects membrane curvature, C-terminal to the PX domain, similar to the sorting nexins SNX1-2, SNX4-8, and SNX32. Both domains have been shown to determine the specific membrane-targeting of SNX1. The specific function of SNX30 has yet to be elucidated.

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gi 665505963  29 LEIDVSNPQTVGVGRGRFTTYEIRVKTNLPIFKLKESTVRRRYSDFEWLRSELE 82
Cdd:cd07283    1 LFVTVDDPKKHVCTMETYITYRVTTKTTRTEFDLPEYSVRRRYQDFDWLRNKLE 54

The phosphoinositide binding Phox Homology domain of SNARE proteins from fungi; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions such as cell signaling, vesicular trafficking, protein sorting, and lipid modification, among others. This subfamily is composed of fungal proteins similar to Saccharomyces cerevisiae Vam7p. They contain an N-terminal PX domain and a C-terminal SNARE domain. The SNARE (Soluble NSF attachment protein receptor) family of proteins are integral membrane proteins that serve as key factors for vesicular trafficking. Vam7p is anchored at the vacuolar membrane through the specific interaction of its PX domain with phosphatidylinositol-3-phosphate (PI3P) present in bilayers. It plays an essential role in vacuole fusion. The PX domain is involved in targeting of proteins to PI-enriched membranes, and may also be involved in protein-protein interaction.

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gi 665505963  38 TVGVGRGRFTTYEIRVKtnlpiFKLKESTVRRRYSDFEWLRSELERE 84
Cdd:cd06897    7 TTSVSPKPYTVYNIQVR-----LPLRSYTVSRRYSEFVALHKQLESE 48

The phosphoinositide binding Phox Homology domain of Sorting Nexin 8 and yeast Mvp1p; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Sorting nexins (SNXs) make up the largest group among PX domain containing proteins. They are involved in regulating membrane traffic and protein sorting in the endosomal system. The PX domain of SNXs binds PIs and targets the protein to PI-enriched membranes. SNXs differ from each other in PI-binding specificity and affinity, and the presence of other protein-protein interaction domains, which help determine subcellular localization and specific function in the endocytic pathway. Some SNXs are localized in early endosome structures such as clathrin-coated pits, while others are located in late structures of the endocytic pathway. SNX8 and the yeast counterpart Mvp1p are involved in sorting and delivery of late-Golgi proteins, such as carboxypeptidase Y, to vacuoles.

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gi 665505963  61 KLKESTVRRRYSDFEWLRSELER 83
Cdd:cd06866   26 KRFKSTVYRRYSDFVWLHEYLLK 48