The phosphoinositide binding Phox Homology domain of Sorting Nexins 17 and 31; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Members of this subfamily include sorting nexin 17 (SNX17), SNX31, and similar proteins. They contain an N-terminal PX domain followed by a truncated FERM (4.1, ezrin, radixin, and moesin) domain and a unique C-terminal region. 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. SNX17 is known to regulate the trafficking and processing of a number of proteins. It binds some members of the low-density lipoprotein receptor (LDLR) family such as LDLR, VLDLR, ApoER2, and others, regulating their endocytosis. It also binds P-selectin and may regulate its lysosomal degradation. SNX17 is highly expressed in neurons. It binds amyloid precursor protein (APP) and may be involved in its intracellular trafficking and processing to amyloid beta peptide, which plays a central role in the pathogenesis of Alzheimer's disease. The biological function of SNX31 is unknown.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209   4 HFCIPVSQQRPDALGGRYVLYSVYLDGFLFCKVRYSQLHRWDEQLRRVFGN-CLPPFPPKYYLAMTTAMAEERRDQLERY 82
Cdd:cd06885   1 HFSIPDTQELSDEGGSTYVAYNIHINGVLHCSVRYSQLHGLNEQLKKEFGNrKLPPFPPKKLLPLTPAQLEERRLQLEKY 80

                        90       100
                ....*....|....*....|....
gi 31981209  83 LQNVTADPRVTRSDVFTEFLTLVQ 106
Cdd:cd06885  81 LQAVVQDPRIANSDIFNSFLLNAQ 104

The phosphoinositide binding Phox Homology domain of Sorting Nexins 17 and 31; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Members of this subfamily include sorting nexin 17 (SNX17), SNX31, and similar proteins. They contain an N-terminal PX domain followed by a truncated FERM (4.1, ezrin, radixin, and moesin) domain and a unique C-terminal region. 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. SNX17 is known to regulate the trafficking and processing of a number of proteins. It binds some members of the low-density lipoprotein receptor (LDLR) family such as LDLR, VLDLR, ApoER2, and others, regulating their endocytosis. It also binds P-selectin and may regulate its lysosomal degradation. SNX17 is highly expressed in neurons. It binds amyloid precursor protein (APP) and may be involved in its intracellular trafficking and processing to amyloid beta peptide, which plays a central role in the pathogenesis of Alzheimer's disease. The biological function of SNX31 is unknown.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209   4 HFCIPVSQQRPDALGGRYVLYSVYLDGFLFCKVRYSQLHRWDEQLRRVFGN-CLPPFPPKYYLAMTTAMAEERRDQLERY 82
Cdd:cd06885   1 HFSIPDTQELSDEGGSTYVAYNIHINGVLHCSVRYSQLHGLNEQLKKEFGNrKLPPFPPKKLLPLTPAQLEERRLQLEKY 80

                        90       100
                ....*....|....*....|....
gi 31981209  83 LQNVTADPRVTRSDVFTEFLTLVQ 106
Cdd:cd06885  81 LQAVVQDPRIANSDIFNSFLLNAQ 104

FERM (Four.1 protein, Ezrin, Radixin, Moesin) domain, F1 sub-domain, found in sorting nexin protein 31 (SNX31); SNX31 is a member of the family of cytoplasmic sorting nexin adaptor proteins that regulate endosomal trafficking of cell surface proteins. It is a novel sorting nexin associated with the uroplakin-degrading multivesicular bodies in terminally differentiated urothelial cells. SNX31 binds multiple beta integrin cytoplasmic domains and regulates beta1 integrin surface levels and stability. SNX31 contains a PX (Phox homology) domain and a FERM (Band 4.1, ezrin, radixin, moesin) domain. The FERM domain is made up of three sub-domains, F1, F2, and F3. This family corresponds to the F1 sub-domain, which is also called the N-terminal ubiquitin-like structural domain of the FERM domain (FERM_N).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209 119 LAVFLPDGRSIKVEGLTSDTAERVLEVMAHKLGLQPDLVGYFGLFLIQCFPEGKLSVVKKLADFELPYTSLQSSEMENCK 198
Cdd:cd16122   8 LDVYLPDGRSVRIDVKTSDTAERVLEVVLDRIGLSRELRGYFSLFLVKGKGKGDFSVVKKLAPFELPYVTLESGEMERCK 87

                        90
                ....*....|.
gi 31981209 199 IGLRKWYLDPA 209
Cdd:cd16122  88 LGIRKWYMDPS 98

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 31981209     35 KVRYSQLHRWDEQLRRVFGNC-LPPFPPKYYL----AMTTAMAEERRDQLERYLQNVTADP-RVTRSDVFTEFLT 103
Cdd:smart00312  31 SRRYSDFLELHSKLKKHFPRSiLPPLPGKKLFgrlnNFSEEFIEKRRRGLEKYLQSLLNHPeLINHSEVVLEFLE 105

The phosphoinositide binding Phox Homology domain of Sorting Nexins 17 and 31; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. Members of this subfamily include sorting nexin 17 (SNX17), SNX31, and similar proteins. They contain an N-terminal PX domain followed by a truncated FERM (4.1, ezrin, radixin, and moesin) domain and a unique C-terminal region. 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. SNX17 is known to regulate the trafficking and processing of a number of proteins. It binds some members of the low-density lipoprotein receptor (LDLR) family such as LDLR, VLDLR, ApoER2, and others, regulating their endocytosis. It also binds P-selectin and may regulate its lysosomal degradation. SNX17 is highly expressed in neurons. It binds amyloid precursor protein (APP) and may be involved in its intracellular trafficking and processing to amyloid beta peptide, which plays a central role in the pathogenesis of Alzheimer's disease. The biological function of SNX31 is unknown.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209   4 HFCIPVSQQRPDALGGRYVLYSVYLDGFLFCKVRYSQLHRWDEQLRRVFGN-CLPPFPPKYYLAMTTAMAEERRDQLERY 82
Cdd:cd06885   1 HFSIPDTQELSDEGGSTYVAYNIHINGVLHCSVRYSQLHGLNEQLKKEFGNrKLPPFPPKKLLPLTPAQLEERRLQLEKY 80

                        90       100
                ....*....|....*....|....
gi 31981209  83 LQNVTADPRVTRSDVFTEFLTLVQ 106
Cdd:cd06885  81 LQAVVQDPRIANSDIFNSFLLNAQ 104

Sorting Nexin 17 FERM C-terminal domain; This is the C-terminal domain of sorting nexin 17 (SNX17) present in Homo sapiens. SNX17 localizes to early endosomes where it directly binds NPX(Y/F) motifs in the target receptors to mediate their rates of endocytic internalization, recycling, or degradation. The domain is known as terminal band 4.1/ezrin/radixin/moesin (FERM) domain. The FERM domain binds directly to the common motif, NPX(Y/F), in the cytoplasmic region of its target proteins.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209   270 GYVQLDPCTCNHPEPGCGAQLSIGNNEISCCITLPNGQIQDIAFQMSRVKCWQVTFLGTllDTDGPQrTLNQNLELRFQY 349
Cdd:pfam18116   1 GYIQFDPCTCDYPEPDSRVTVSVGNNELNCCITLPEKETEEAAFKVTRMRCWRVTALDN--KSMSPQ-DNEQGLELSFEY 77

                          90       100       110
                  ....*....|....*....|....*....|..
gi 31981209   350 SED-SCQQWFVIYTKQAFFLSSCLKKMISERM 380
Cdd:pfam18116  78 LFSkDELKWITIASEQAILLSMCLQSMVDELL 109

FERM (Four.1 protein, Ezrin, Radixin, Moesin) domain, F1 sub-domain, found in PX-FERM family sorting nexin proteins; This family includes three endosome-associated PX (Phox homology) and FERM (Band 4.1, ezrin, radixin, moesin) domain-containing proteins called sorting nexin (SNX) 17, SNX27, and SNX31, which are modular peripheral membrane proteins acting as central scaffolds mediating protein-lipid interactions, cargo binding, and regulatory protein recruitment. They are key regulators of endosomal recycling and bind conserved NPX(Y/F) peptide sorting motifs in transmembrane cargos via an atypical FERM domain. The FERM domain is made up of three sub-domains, F1, F2, and F3. This family corresponds to the F1 sub-domain, which is also called the N-terminal ubiquitin-like structural domain of the FERM domain (FERM_N).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209 115 QNVELAVFLPDGRSIKVEGLTSDTAERVLEVMAHKLGLQPDLVGYFGLFLIQCFPEGKLSVVKKLADFELPYTSLQSSEM 194
Cdd:cd17109   1 SDVELRVALPNGQTVTVRVKTSDTTEQVLEAVAAKVGLDSTLVGYFALFLVRSHSEGKLSFVRKLAPFELPYVSYISNYT 80

                        90
                ....*....|...
gi 31981209 195 ENCKIGLRKWYLD 207
Cdd:cd17109  81 PGTKLTLRKWYFT 93

FERM (Four.1 protein, Ezrin, Radixin, Moesin) domain, F1 sub-domain, found in sorting nexin protein 17 (SNX17); SNX17 is a member of the family of cytoplasmic sorting nexin adaptor proteins that regulate endosomal trafficking of cell surface proteins. It localizes to early endosomes, and plays an important role in mediating endocytic internalization, recycling, and/or protection from lysosomal degradation of NPxY-motif containing cell surface proteins including amyloid precursor protein (APP), P-selectin, beta1-integrin, low density lipoprotein receptor (LDLR), LDLR related protein (Lrp1), ApoER2, and FEEL1. SNX17 also affects T cell activation by regulating T cell receptor and integrin recycling. SNX17 contains a PX (Phox homology) domain and a FERM (Band 4.1, ezrin, radixin, moesin) domain. The FERM domain is made up of three sub-domains, F1, F2, and F3. This family corresponds to the F1 sub-domain, which is also called the N-terminal ubiquitin-like structural domain of the FERM domain (FERM_N).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209 115 QNVELAVFLPDGRSIKVEGLTSDTAERVLEVMAHKLGLQPDLVGYFGLFLIQCFPEGKLSVVKKLADFELPYTSLQSSEM 194
Cdd:cd16121   1 EEVSLDVFLMNGQKITVNISSTDQTDDVLEAVASKLGLPEELVYYFALFLVKKDDDGNNTIVRKLQDFESPYLSLKSAGK 80

                        90
                ....*....|...
gi 31981209 195 ENCKIGLRKWYLD 207
Cdd:cd16121  81 GSHRIVLRKSYWD 93

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.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209   4 HFCIPVSQQRPDaLGGRYVLYSVYLDGFLFCKV----RYSQLHRWDEQLRRVFGNC-LPPFPPKYYLA-MTTAMAEERRD 77
Cdd:cd06093   1 SVSIPDYEKVKD-GGKKYVVYIIEVTTQGGEEWtvyrRYSDFEELHEKLKKKFPGViLPPLPPKKLFGnLDPEFIEERRK 79

                        90       100
                ....*....|....*....|....*..
gi 31981209  78 QLERYLQNVTADPRVTRSDVFTEFLTL 104
Cdd:cd06093  80 QLEQYLQSLLNHPELRNSEELKEFLEL 106

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

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 31981209     35 KVRYSQLHRWDEQLRRVFGNC-LPPFPPKYYL----AMTTAMAEERRDQLERYLQNVTADP-RVTRSDVFTEFLT 103
Cdd:smart00312  31 SRRYSDFLELHSKLKKHFPRSiLPPLPGKKLFgrlnNFSEEFIEKRRRGLEKYLQSLLNHPeLINHSEVVLEFLE 105

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.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209   3 MHFCIPVSQQRPdalgGRYVLYSVYLDGFLF---CKVRYSQLHRWDEQLRRVFGNCLP-PFPPKYYLAMTT---AMAEER 75
Cdd:cd06897   1 LEISIPTTSVSP----KPYTVYNIQVRLPLRsytVSRRYSEFVALHKQLESEVGIEPPyPLPPKSWFLSTSsnpKLVEER 76

                        90       100       110
                ....*....|....*....|....*....|.
gi 31981209  76 RDQLERYLQ--NVTADPRVTRSDVFTEFLTL 104
Cdd:cd06897  77 RVGLEAFLRalLNDEDSRWRNSPAVKEFLNL 107

The phosphoinositide binding Phox Homology domain of fungal Sorting Nexins 41 and 42; 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. SNX41 and SNX42 (also called Atg20p) form dimers with SNX4, and are required in protein recycling from the sorting endosome (post-Golgi endosome) back to the late Golgi in yeast.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209  15 DALGGRYVLYSVYLDGFLfCKVRYSQLHRWDEQLRRVFGNCL-PPFPPK-----YYLAMTTA-----MAEERRDQLERYL 83
Cdd:cd06867  12 EGGSGSYIVYVIRLGGSE-VKRRYSEFESLRKNLTRLYPTLIiPPIPEKhslkdYAKKPSKAkndakIIERRKRMLQRFL 90

                        90
                ....*....|....*....
gi 31981209  84 QNVTADPRVTRSDVFTEFL 102
Cdd:cd06867  91 NRCLQHPILRNDIVFQKFL 109

The phosphoinositide binding Phox Homology domain of yeast MDM1p; The PX domain is a phosphoinositide binding (PI) module present in many proteins with diverse functions such as cell signaling, vesicular trafficking, protein sorting, and lipid modification, among others. Yeast MDM1p is a filament-like protein localized in punctate structures distributed throughout the cytoplasm. It plays an important role in nuclear and mitochondrial transmission to daughter buds. Members of this subfamily show similar domain architectures as some sorting nexins (SNXs). Some members are similar to SNX19 in that they contain an N-terminal PXA domain, a central PX domain, and a C-terminal domain that is conserved in some SNXs. Others are similar to SNX13 and SNX14, which also harbor these three domains as well as a regulator of G protein signaling (RGS) domain in between the PXA and PX domains. 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.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 31981209  37 RYSQLHRWDEQLRRVFGN-CLPPFPPKY---YLAMTTAMAEERRDQLERYLQNVTADPRVTRSDVFTEFLT 103
Cdd:cd06876  62 RYSEFLELHKYLKKRYPGvLKLDFPQKRkisLKYSKTLLVEERRKALEKYLQELLKIPEVCEDEEFRKFLS 132

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.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 31981209  37 RYSQLHRWDEQLRRVF-GNCLPPFPPKYYLAMTTAMA---EERRDQLERYLQNVTADPRVTRSDVFTEFLT 103
Cdd:cd06859  42 RYSDFLWLYERLVEKYpGRIVPPPPEKQAVGRFKVKFefiEKRRAALERFLRRIAAHPVLRKDPDFRLFLE 112

The phosphoinositide binding Phox Homology domain of uncharacterized plant proteins; The PX domain is a phosphoinositide (PI) binding module involved in targeting proteins to PI-enriched membranes. Members in this subfamily are uncharacterized fungal proteins containing a PX domain. PX domain harboring proteins 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. In addition to protein-lipid interaction, the PX domain may also be involved in protein-protein interaction.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 31981209  37 RYSQLHRWDEQLRRVF-GNCLPPFPPKYYLAMTT-AMAEERRDQLERYLQNVTADPRVTRSDVFTEFLTL 104
Cdd:cd06879  68 RFNDFLKLHTDLKKLFpKKKLPAAPPKGLLRMKNrALLEERRHSLEEWMGKLLSDIDLSRSVPVASFLEL 137

The phosphoinositide binding Phox Homology Domain of Class II Phosphoinositide 3-Kinases; The PX domain is a phosphoinositide (PI) binding module present in many proteins with diverse functions. The Phosphoinositide 3-Kinase (PI3K) family of enzymes catalyzes the phosphorylation of the 3-hydroxyl group of the inositol ring of phosphatidylinositol. PI3Ks play an important role in a variety of fundamental cellular processes, including cell motility, the Ras pathway, vesicle trafficking and secretion, immune cell activation and apoptosis. They are also involved in the regulation of clathrin-mediated membrane trafficking as well as ATP-dependent priming of neurosecretory granule exocytosis. PI3Ks are divided into three main classes (I, II, and III) based on their substrate specificity, regulation, and domain structure. Class II PI3Ks preferentially use PI as a substrate to produce PI3P, but can also phosphorylate PI4P to produce PI(3,4)P2. They function as monomers and do not associate with any regulatory subunits. Class II enzymes contain an N-terminal Ras binding domain, a lipid binding C2 domain, a PI3K homology domain of unknown function, an ATP-binding cataytic domain, a PX domain, and a second C2 domain at the C-terminus. Class II PI3Ks include three vertebrate isoforms (alpha, beta, and gamma), the Drosophila PI3K_68D, and similar proteins.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 31981209  37 RYSQLHRWDEQLRRVF-GNCLPPFPPKYYLAMTT--AMAEERRDQLERYLQNV-TADPRVTRSD-VFTEFLTL 104
Cdd:cd06883  37 TFEEFQELHNKLSLLFpSLKLPSFPARVVLGRSHikQVAERRKIELNSYLKSLfNASPEVAESDlVYTFFHPL 109

The phosphoinositide binding Phox Homology domain of KIF16B kinesin or Sorting Nexin 23; 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. KIF16B, also called sorting nexin 23 (SNX23), is a family-3 kinesin which harbors an N-terminal kinesin motor domain containing ATP and microtubule binding sites, a ForkHead Associated (FHA) domain, and a C-terminal PX domain. The PX domain of KIF16B binds to phosphatidylinositol-3-phosphate (PI3P) in early endosomes and plays a role in the transport of early endosomes to the plus end of microtubules. By regulating early endosome plus end motility, KIF16B modulates the balance between recycling and degradation of receptors. 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.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|..
gi 31981209  37 RYSQLHRWDEQLRRVFG--NCLPpFPPK-YYLAMTTAMAEERRDQLERYLQN 85
Cdd:cd06874  37 RYSRFRELHKTMKLKYPevAALE-FPPKkLFGNKSERVAKERRRQLETYLRN 87