NCBI Home Page NCBI Site Search page NCBI Guide that lists and describes the NCBI resources
Conserved domains on  [gi|71773201|ref|NP_001025189|]
View 

adenine phosphoribosyltransferase isoform b [Homo sapiens]

Protein Classification

type I phosphoribosyltransferase( domain architecture ID 27)

type I phosphoribosyltransferase similar to phosphoribosyltransferases with specificities for hypoxanthine, guanine, and/or xanthine

Graphical summary

 Zoom to residue level

show extra options »

Show site features     Horizontal zoom: ×

List of domain hits

 Name Accession Description Interval E-value
PRTases_typeI super family cl00309
Phosphoribosyl transferase (PRT)-type I domain; Phosphoribosyl transferase (PRT) domain. The ...
 9-133 3.96e-69

Phosphoribosyl transferase (PRT)-type I domain; Phosphoribosyl transferase (PRT) domain. The type I PRTases are identified by a conserved PRPP binding motif which features two adjacent acidic residues surrounded by one or more hydrophobic residue. PRTases catalyze the displacement of the alpha-1'-pyrophosphate of 5-phosphoribosyl-alpha1-pyrophosphate (PRPP) by a nitrogen-containing nucleophile. The reaction products are an alpha-1 substituted ribose-5'-phosphate and a free pyrophosphate (PP). PRPP, an activated form of ribose-5-phosphate, is a key metabolite connecting nucleotide synthesis and salvage pathways. The type I PRTase family includes a range of diverse phosphoribosyl transferase enzymes and regulatory proteins of the nucleotide synthesis and salvage pathways, including adenine phosphoribosyltransferase EC:2.4.2.7., hypoxanthine-guanine-xanthine phosphoribosyltransferase, hypoxanthine phosphoribosyltransferase EC:2.4.2.8., ribose-phosphate pyrophosphokinase EC:2.7.6.1., amidophosphoribosyltransferase EC:2.4.2.14., orotate phosphoribosyltransferase EC:2.4.2.10., uracil phosphoribosyltransferase EC:2.4.2.9., and xanthine-guanine phosphoribosyltransferase EC:2.4.2.22.


The actual alignment was detected with superfamily member TIGR01090:

Pssm-ID: 444823  Cd Length: 169  Bit Score: 205.20  E-value: 3.96e-69
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201     9 VEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKATHggrIDYIAGLDSRGFLFGPSLAQELGLGCVLIRK 88
Cdd:TIGR01090   1 LKQAIRSIPDFPKKGILFRDITPLLNNPELFRFLIDLLVERYKDAN---IDYIVGPEARGFIFGAALAYKLGVGFVPVRK 77

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 71773201    89 RGKLPGPTLWASYSLEYGKAELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:TIGR01090  78 PGKLPGETISASYDLEYGKDVLEIHKDAIKPGQRVLIVDDLLATG 122
 
Name Accession Description Interval E-value
apt TIGR01090
adenine phosphoribosyltransferase; A phylogenetic analysis suggested omitting the ...
 9-133 3.96e-69

adenine phosphoribosyltransferase; A phylogenetic analysis suggested omitting the bi-directional best hit homologs from the spirochetes from the seed for this model and making only tentative predictions of adenine phosphoribosyltransferase function for this lineage. The trusted cutoff score is made high for this reason. Most proteins scoring between the trusted and noise cutoffs are likely to act as adenine phosphotransferase. [Purines, pyrimidines, nucleosides, and nucleotides, Salvage of nucleosides and nucleotides]


Pssm-ID: 273437  Cd Length: 169  Bit Score: 205.20  E-value: 3.96e-69
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201     9 VEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKATHggrIDYIAGLDSRGFLFGPSLAQELGLGCVLIRK 88
Cdd:TIGR01090   1 LKQAIRSIPDFPKKGILFRDITPLLNNPELFRFLIDLLVERYKDAN---IDYIVGPEARGFIFGAALAYKLGVGFVPVRK 77

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 71773201    89 RGKLPGPTLWASYSLEYGKAELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:TIGR01090  78 PGKLPGETISASYDLEYGKDVLEIHKDAIKPGQRVLIVDDLLATG 122
PRK02304 PRK02304
adenine phosphoribosyltransferase; Provisional
 6-133 4.12e-63

adenine phosphoribosyltransferase; Provisional


Pssm-ID: 235028  Cd Length: 175  Bit Score: 190.29  E-value: 4.12e-63
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201    6 LQLVEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKathGGRIDYIAGLDSRGFLFGPSLAQELGLGCVL 85
Cdd:PRK02304   3 LEDLKSSIRTIPDFPKPGILFRDITPLLADPEAFREVIDALVERYK---DADIDKIVGIEARGFIFGAALAYKLGIGFVP 79

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|....*...
gi 71773201   86 IRKRGKLPGPTLWASYSLEYGKAELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:PRK02304  80 VRKPGKLPRETISESYELEYGTDTLEIHKDAIKPGDRVLIVDDLLATG 127
Apt COG0503
Adenine/guanine phosphoribosyltransferase or related PRPP-binding protein [Nucleotide ...
 7-133 1.06e-55

Adenine/guanine phosphoribosyltransferase or related PRPP-binding protein [Nucleotide transport and metabolism]; Adenine/guanine phosphoribosyltransferase or related PRPP-binding protein is part of the Pathway/BioSystem: Purine salvage


Pssm-ID: 440269  Cd Length: 171  Bit Score: 171.41  E-value: 1.06e-55
                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201   7 QLVEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKathGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLI 86
Cdd:COG0503   1 EDLKDLIRDIPDFPKPGILFRDITPLLGDPELFRAAGDELAERFA---DKGIDKVVGIEARGFILAAALAYALGVPFVPA 77

                        90       100       110       120
                ....*....|....*....|....*....|....*....|....*...
gi 71773201  87 RKRGKLPGPTLWASYSLEYGK-AELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:COG0503  78 RKPGKLPGETVSEEYDLEYGTgDTLELHKDALKPGDRVLIVDDLLATG 125
PRTases_typeI cd06223
Phosphoribosyl transferase (PRT)-type I domain; Phosphoribosyl transferase (PRT) domain. The ...
 42-133 1.26e-16

Phosphoribosyl transferase (PRT)-type I domain; Phosphoribosyl transferase (PRT) domain. The type I PRTases are identified by a conserved PRPP binding motif which features two adjacent acidic residues surrounded by one or more hydrophobic residue. PRTases catalyze the displacement of the alpha-1'-pyrophosphate of 5-phosphoribosyl-alpha1-pyrophosphate (PRPP) by a nitrogen-containing nucleophile. The reaction products are an alpha-1 substituted ribose-5'-phosphate and a free pyrophosphate (PP). PRPP, an activated form of ribose-5-phosphate, is a key metabolite connecting nucleotide synthesis and salvage pathways. The type I PRTase family includes a range of diverse phosphoribosyl transferase enzymes and regulatory proteins of the nucleotide synthesis and salvage pathways, including adenine phosphoribosyltransferase EC:2.4.2.7., hypoxanthine-guanine-xanthine phosphoribosyltransferase, hypoxanthine phosphoribosyltransferase EC:2.4.2.8., ribose-phosphate pyrophosphokinase EC:2.7.6.1., amidophosphoribosyltransferase EC:2.4.2.14., orotate phosphoribosyltransferase EC:2.4.2.10., uracil phosphoribosyltransferase EC:2.4.2.9., and xanthine-guanine phosphoribosyltransferase EC:2.4.2.22.


Pssm-ID: 206754 [Multi-domain]  Cd Length: 130  Bit Score: 70.50  E-value: 1.26e-16
                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201  42 AIGLLARHLKAtHGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLIRKRGKLPGPTLWASYsleygkaELEIQKDALEPGQ 121
Cdd:cd06223   1 AGRLLAEEIRE-DLLEPDVVVGILRGGLPLAAALARALGLPLAFIRKERKGPGRTPSEPY-------GLELPLGGDVKGK 72

                        90
                ....*....|..
gi 71773201 122 RVVVVDDLLATG 133
Cdd:cd06223  73 RVLLVDDVIATG 84
Pribosyltran pfam00156
Phosphoribosyl transferase domain; This family includes a range of diverse phosphoribosyl ...
 32-133 3.96e-11

Phosphoribosyl transferase domain; This family includes a range of diverse phosphoribosyl transferase enzymes. This family includes: Adenine phosphoribosyl-transferase EC:2.4.2.7. Hypoxanthine-guanine-xanthine phosphoribosyl-transferase. Hypoxanthine phosphoribosyl-transferase EC:2.4.2.8. Ribose-phosphate pyrophosphokinase i EC:2.7.6.1. Amidophosphoribosyltransferase EC:2.4.2.14. Orotate phosphoribosyl-transferase EC:2.4.2.10. Uracil phosphoribosyl-transferase EC:2.4.2.9. Xanthine-guanine phosphoribosyl-transferase EC:2.4.2.22. In Arabidopsis, At the very N-terminus of this domain is the P-Loop NTPase domain.


Pssm-ID: 425489 [Multi-domain]  Cd Length: 150  Bit Score: 56.99  E-value: 3.96e-11
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201    32 VLKDPASFRAAIGLLARHLKaTHGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLIRKRGKLPGPTLWASYsleygkaele 111
Cdd:pfam00156   5 ILDNPAILKAVARLAAQINE-DYGGKPDVVVGILRGGLPFAGILARRLDVPLAFVRKVSYNPDTSEVMKT---------- 73

                          90       100
                  ....*....|....*....|..
gi 71773201   112 IQKDALEPGQRVVVVDDLLATG 133
Cdd:pfam00156  74 SSALPDLKGKTVLIVDDILDTG 95
 
Name Accession Description Interval E-value
apt TIGR01090
adenine phosphoribosyltransferase; A phylogenetic analysis suggested omitting the ...
 9-133 3.96e-69

adenine phosphoribosyltransferase; A phylogenetic analysis suggested omitting the bi-directional best hit homologs from the spirochetes from the seed for this model and making only tentative predictions of adenine phosphoribosyltransferase function for this lineage. The trusted cutoff score is made high for this reason. Most proteins scoring between the trusted and noise cutoffs are likely to act as adenine phosphotransferase. [Purines, pyrimidines, nucleosides, and nucleotides, Salvage of nucleosides and nucleotides]


Pssm-ID: 273437  Cd Length: 169  Bit Score: 205.20  E-value: 3.96e-69
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201     9 VEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKATHggrIDYIAGLDSRGFLFGPSLAQELGLGCVLIRK 88
Cdd:TIGR01090   1 LKQAIRSIPDFPKKGILFRDITPLLNNPELFRFLIDLLVERYKDAN---IDYIVGPEARGFIFGAALAYKLGVGFVPVRK 77

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 71773201    89 RGKLPGPTLWASYSLEYGKAELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:TIGR01090  78 PGKLPGETISASYDLEYGKDVLEIHKDAIKPGQRVLIVDDLLATG 122
PRK02304 PRK02304
adenine phosphoribosyltransferase; Provisional
 6-133 4.12e-63

adenine phosphoribosyltransferase; Provisional


Pssm-ID: 235028  Cd Length: 175  Bit Score: 190.29  E-value: 4.12e-63
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201    6 LQLVEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKathGGRIDYIAGLDSRGFLFGPSLAQELGLGCVL 85
Cdd:PRK02304   3 LEDLKSSIRTIPDFPKPGILFRDITPLLADPEAFREVIDALVERYK---DADIDKIVGIEARGFIFGAALAYKLGIGFVP 79

                         90       100       110       120
                 ....*....|....*....|....*....|....*....|....*...
gi 71773201   86 IRKRGKLPGPTLWASYSLEYGKAELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:PRK02304  80 VRKPGKLPRETISESYELEYGTDTLEIHKDAIKPGDRVLIVDDLLATG 127
Apt COG0503
Adenine/guanine phosphoribosyltransferase or related PRPP-binding protein [Nucleotide ...
 7-133 1.06e-55

Adenine/guanine phosphoribosyltransferase or related PRPP-binding protein [Nucleotide transport and metabolism]; Adenine/guanine phosphoribosyltransferase or related PRPP-binding protein is part of the Pathway/BioSystem: Purine salvage


Pssm-ID: 440269  Cd Length: 171  Bit Score: 171.41  E-value: 1.06e-55
                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201   7 QLVEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKathGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLI 86
Cdd:COG0503   1 EDLKDLIRDIPDFPKPGILFRDITPLLGDPELFRAAGDELAERFA---DKGIDKVVGIEARGFILAAALAYALGVPFVPA 77

                        90       100       110       120
                ....*....|....*....|....*....|....*....|....*...
gi 71773201  87 RKRGKLPGPTLWASYSLEYGK-AELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:COG0503  78 RKPGKLPGETVSEEYDLEYGTgDTLELHKDALKPGDRVLIVDDLLATG 125
PLN02293 PLN02293
adenine phosphoribosyltransferase
 2-133 6.85e-43

adenine phosphoribosyltransferase


Pssm-ID: 177930  Cd Length: 187  Bit Score: 139.42  E-value: 6.85e-43
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201    2 ADSELQLVEQRIRSFPDFPTPGVVFRDISPVLKDPASFRAAIGLLARHLKathGGRIDYIAGLDSRGFLFGPSLAQELGL 81
Cdd:PLN02293  10 GDPRLQGISSAIRVVPDFPKPGIMFQDITTLLLDPKAFKDTIDLFVERYR---DMGISVVAGIEARGFIFGPPIALAIGA 86

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|..
gi 71773201   82 GCVLIRKRGKLPGPTLWASYSLEYGKAELEIQKDALEPGQRVVVVDDLLATG 133
Cdd:PLN02293  87 KFVPLRKPGKLPGEVISEEYVLEYGTDCLEMHVGAVEPGERALVIDDLIATG 138
PRTases_typeI cd06223
Phosphoribosyl transferase (PRT)-type I domain; Phosphoribosyl transferase (PRT) domain. The ...
 42-133 1.26e-16

Phosphoribosyl transferase (PRT)-type I domain; Phosphoribosyl transferase (PRT) domain. The type I PRTases are identified by a conserved PRPP binding motif which features two adjacent acidic residues surrounded by one or more hydrophobic residue. PRTases catalyze the displacement of the alpha-1'-pyrophosphate of 5-phosphoribosyl-alpha1-pyrophosphate (PRPP) by a nitrogen-containing nucleophile. The reaction products are an alpha-1 substituted ribose-5'-phosphate and a free pyrophosphate (PP). PRPP, an activated form of ribose-5-phosphate, is a key metabolite connecting nucleotide synthesis and salvage pathways. The type I PRTase family includes a range of diverse phosphoribosyl transferase enzymes and regulatory proteins of the nucleotide synthesis and salvage pathways, including adenine phosphoribosyltransferase EC:2.4.2.7., hypoxanthine-guanine-xanthine phosphoribosyltransferase, hypoxanthine phosphoribosyltransferase EC:2.4.2.8., ribose-phosphate pyrophosphokinase EC:2.7.6.1., amidophosphoribosyltransferase EC:2.4.2.14., orotate phosphoribosyltransferase EC:2.4.2.10., uracil phosphoribosyltransferase EC:2.4.2.9., and xanthine-guanine phosphoribosyltransferase EC:2.4.2.22.


Pssm-ID: 206754 [Multi-domain]  Cd Length: 130  Bit Score: 70.50  E-value: 1.26e-16
                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201  42 AIGLLARHLKAtHGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLIRKRGKLPGPTLWASYsleygkaELEIQKDALEPGQ 121
Cdd:cd06223   1 AGRLLAEEIRE-DLLEPDVVVGILRGGLPLAAALARALGLPLAFIRKERKGPGRTPSEPY-------GLELPLGGDVKGK 72

                        90
                ....*....|..
gi 71773201 122 RVVVVDDLLATG 133
Cdd:cd06223  73 RVLLVDDVIATG 84
PRK12560 PRK12560
adenine phosphoribosyltransferase; Provisional
 9-133 1.92e-15

adenine phosphoribosyltransferase; Provisional


Pssm-ID: 183595  Cd Length: 187  Bit Score: 69.04  E-value: 1.92e-15
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201    9 VEQRIRSFPDFPTPGVV--FRDISPVLKdPASFRAAIGLLARHLKAthggRIDYIAGLDSRGFLFGPSLAQelgLGCVLI 86
Cdd:PRK12560   6 LYKNARVVNSGKALTTVneFTDQLPALR-PKVLKETAKEIIKYIDK----DIDKIVTEEDKGAPLATPVSL---LSGKPL 77

                         90       100       110       120       130
                 ....*....|....*....|....*....|....*....|....*....|
gi 71773201   87 RKRGKLPGPTLWASYS-LEYGKAELE--IQKDALEPGQRVVVVDDLLATG 133
Cdd:PRK12560  78 AMARWYPYSLSELNYNvVEIGSEYFEgvVYLNGIEKGDRVAIIDDTLSTG 127
Pribosyltran pfam00156
Phosphoribosyl transferase domain; This family includes a range of diverse phosphoribosyl ...
 32-133 3.96e-11

Phosphoribosyl transferase domain; This family includes a range of diverse phosphoribosyl transferase enzymes. This family includes: Adenine phosphoribosyl-transferase EC:2.4.2.7. Hypoxanthine-guanine-xanthine phosphoribosyl-transferase. Hypoxanthine phosphoribosyl-transferase EC:2.4.2.8. Ribose-phosphate pyrophosphokinase i EC:2.7.6.1. Amidophosphoribosyltransferase EC:2.4.2.14. Orotate phosphoribosyl-transferase EC:2.4.2.10. Uracil phosphoribosyl-transferase EC:2.4.2.9. Xanthine-guanine phosphoribosyl-transferase EC:2.4.2.22. In Arabidopsis, At the very N-terminus of this domain is the P-Loop NTPase domain.


Pssm-ID: 425489 [Multi-domain]  Cd Length: 150  Bit Score: 56.99  E-value: 3.96e-11
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201    32 VLKDPASFRAAIGLLARHLKaTHGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLIRKRGKLPGPTLWASYsleygkaele 111
Cdd:pfam00156   5 ILDNPAILKAVARLAAQINE-DYGGKPDVVVGILRGGLPFAGILARRLDVPLAFVRKVSYNPDTSEVMKT---------- 73

                          90       100
                  ....*....|....*....|..
gi 71773201   112 IQKDALEPGQRVVVVDDLLATG 133
Cdd:pfam00156  74 SSALPDLKGKTVLIVDDILDTG 95
PyrE COG0461
Orotate phosphoribosyltransferase [Nucleotide transport and metabolism]; Orotate ...
 28-133 2.67e-09

Orotate phosphoribosyltransferase [Nucleotide transport and metabolism]; Orotate phosphoribosyltransferase is part of the Pathway/BioSystem: Pyrimidine biosynthesis


Pssm-ID: 440229  Cd Length: 201  Bit Score: 52.85  E-value: 2.67e-09
                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201  28 DISPVLKDPASFRAAIGLLARHLKAtHGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLIRKRGKlpgptlwasyslEYGK 107
Cdd:COG0461  35 DCRLVLSYPEALELLGEALAELIKE-LGPEFDAVAGPATGGIPLAAAVARALGLPAIFVRKEAK------------DHGT 101

                        90       100
                ....*....|....*....|....*..
gi 71773201 108 -AELEiqkDALEPGQRVVVVDDLLATG 133
Cdd:COG0461 102 gGQIE---GGLLPGERVLVVEDVITTG 125
pyrE PRK00455
orotate phosphoribosyltransferase; Validated
 31-133 5.81e-06

orotate phosphoribosyltransferase; Validated


Pssm-ID: 234771  Cd Length: 202  Bit Score: 43.61  E-value: 5.81e-06
                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 71773201   31 PVLKDPASFRAAIGLLARHLKAtHGGRIDYIAGLDSRGFLFGPSLAQELGLGCVLIRKRGKlpgptlwasyslEYGK-AE 109
Cdd:PRK00455  39 KLLSYPEALALLGRFLAEAIKD-SGIEFDVVAGPATGGIPLAAAVARALDLPAIFVRKEAK------------DHGEgGQ 105

                         90       100
                 ....*....|....*....|....
gi 71773201  110 LEIqkdALEPGQRVVVVDDLLATG 133
Cdd:PRK00455 106 IEG---RRLFGKRVLVVEDVITTG 126
 
Blast search parameters
Data Source: Precalculated data, version = cdd.v.3.21
Preset Options:Database: CDSEARCH/cdd   Low complexity filter: no  Composition Based Adjustment: yes   E-value threshold: 0.01

References:

  • Wang J et al. (2023), "The conserved domain database in 2023", Nucleic Acids Res.51(D)384-8.
  • Lu S et al. (2020), "The conserved domain database in 2020", Nucleic Acids Res.48(D)265-8.
  • Marchler-Bauer A et al. (2017), "CDD/SPARCLE: functional classification of proteins via subfamily domain architectures.", Nucleic Acids Res.45(D)200-3.
Help | Disclaimer | Write to the Help Desk
NCBI | NLM | NIH