NCBI Home Page NCBI Site Search page NCBI Guide that lists and describes the NCBI resources
Conserved domains on  [gi|240256383|ref|NP_198793|]
View 

Restriction endonuclease, type II-like superfamily protein [Arabidopsis thaliana]

Protein Classification

crossover junction endonuclease MUS81( domain architecture ID 15338741)

crossover junction endonuclease MUS81 interacts with EME1 to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick

Graphical summary

 Zoom to residue level

show extra options »

Show site features     Horizontal zoom: ×

List of domain hits

Name Accession Description Interval E-value
XPF_nuclease_Mus81 cd20074
XPF-like nuclease domain of Mus81; Mus81 is a crossover junction endonuclease that interacts ...
1026-1140 3.20e-39

XPF-like nuclease domain of Mus81; Mus81 is a crossover junction endonuclease that interacts with Eme1 and Eme2 to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. The typical substrates include 3'-flap structures, replication forks and nicked Holliday junctions. Mus81 may be required in mitosis for the processing of stalled or collapsed replication forks. Mus81 consists of the active nuclease domain with the GDX(n)ERKX(3)D motif which is required for metal-dependent endonuclease activity and two helix-hairpin-helix (HhH2) domains.


:

Pssm-ID: 410850 [Multi-domain]  Cd Length: 150  Bit Score: 143.01  E-value: 3.20e-39
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383 1026 YDVILILDDREQFATKGHKYQQD-------------------------------EYVLDFIVERKNVDDMRSSIMDNRYK 1074
Cdd:cd20074     2 YEVVLLVDNREVKGKKDRDYFQReleklgvkvetrslpvgdflwvarhksdtgeELVLDYIVERKRLDDLASSIKDGRYH 81
                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 240256383 1075 DQKLRLQRSGIKKLIYILEGDPNQSKT---AESIKTACFTTEILEGFDVVRTNGLGETLRKYGYLTKSI 1140
Cdd:cd20074    82 EQKFRLKRSGIKNVIYLVEGDGSAQSGglpEEALKTALANTQVVDGFFVKRTKSLDETVRYLARLTRAL 150
WH_MUS81 cd21036
winged helix domain found in crossover junction endonuclease MUS81 and similar proteins; MUS81 ...
838-939 1.83e-27

winged helix domain found in crossover junction endonuclease MUS81 and similar proteins; MUS81 is a crossover junction endonuclease that interacts with EME1 (essential meiotic structure-specific endonuclease 1) and EME2, to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. The MUS80-EME1 endonuclease maintains genomic integrity in metazoans by cleaving branched DNA structures that can form during mitosis and fission yeast meiosis, and during processing of damaged replication folks. This model corresponds to the winged helix (WH) domain of MUS81, which is responsible for DNA binding. It comprises four helices and two beta strands.


:

Pssm-ID: 411029  Cd Length: 94  Bit Score: 107.23  E-value: 1.83e-27
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383  838 YKPQRNTAAYA-LLTLHRFKTANGKKLMRKQKLMDAADASGLSHVSIApekgkgkaglgtSKREWYSGWSCMSKLIEKGL 916
Cdd:cd21036     1 YVPKYRSGAYAiLLALYKLDKEPGKGGLTKEELIRRAQPYCDSSFTIP------------DPGSFYTAWSSMKTLIKKGL 68
                          90       100
                  ....*....|....*....|...
gi 240256383  917 VVKFSNPAKYMLTVEGRNVADDL 939
Cdd:cd21036    69 VYKEGRPARYSLTEEGRELAEKL 91
 
Name Accession Description Interval E-value
XPF_nuclease_Mus81 cd20074
XPF-like nuclease domain of Mus81; Mus81 is a crossover junction endonuclease that interacts ...
1026-1140 3.20e-39

XPF-like nuclease domain of Mus81; Mus81 is a crossover junction endonuclease that interacts with Eme1 and Eme2 to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. The typical substrates include 3'-flap structures, replication forks and nicked Holliday junctions. Mus81 may be required in mitosis for the processing of stalled or collapsed replication forks. Mus81 consists of the active nuclease domain with the GDX(n)ERKX(3)D motif which is required for metal-dependent endonuclease activity and two helix-hairpin-helix (HhH2) domains.


Pssm-ID: 410850 [Multi-domain]  Cd Length: 150  Bit Score: 143.01  E-value: 3.20e-39
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383 1026 YDVILILDDREQFATKGHKYQQD-------------------------------EYVLDFIVERKNVDDMRSSIMDNRYK 1074
Cdd:cd20074     2 YEVVLLVDNREVKGKKDRDYFQReleklgvkvetrslpvgdflwvarhksdtgeELVLDYIVERKRLDDLASSIKDGRYH 81
                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 240256383 1075 DQKLRLQRSGIKKLIYILEGDPNQSKT---AESIKTACFTTEILEGFDVVRTNGLGETLRKYGYLTKSI 1140
Cdd:cd20074    82 EQKFRLKRSGIKNVIYLVEGDGSAQSGglpEEALKTALANTQVVDGFFVKRTKSLDETVRYLARLTRAL 150
WH_MUS81 cd21036
winged helix domain found in crossover junction endonuclease MUS81 and similar proteins; MUS81 ...
838-939 1.83e-27

winged helix domain found in crossover junction endonuclease MUS81 and similar proteins; MUS81 is a crossover junction endonuclease that interacts with EME1 (essential meiotic structure-specific endonuclease 1) and EME2, to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. The MUS80-EME1 endonuclease maintains genomic integrity in metazoans by cleaving branched DNA structures that can form during mitosis and fission yeast meiosis, and during processing of damaged replication folks. This model corresponds to the winged helix (WH) domain of MUS81, which is responsible for DNA binding. It comprises four helices and two beta strands.


Pssm-ID: 411029  Cd Length: 94  Bit Score: 107.23  E-value: 1.83e-27
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383  838 YKPQRNTAAYA-LLTLHRFKTANGKKLMRKQKLMDAADASGLSHVSIApekgkgkaglgtSKREWYSGWSCMSKLIEKGL 916
Cdd:cd21036     1 YVPKYRSGAYAiLLALYKLDKEPGKGGLTKEELIRRAQPYCDSSFTIP------------DPGSFYTAWSSMKTLIKKGL 68
                          90       100
                  ....*....|....*....|...
gi 240256383  917 VVKFSNPAKYMLTVEGRNVADDL 939
Cdd:cd21036    69 VYKEGRPARYSLTEEGRELAEKL 91
ERCC4 pfam02732
ERCC4 domain; This domain is a family of nucleases. The family includes EME1 which is an ...
1040-1129 2.14e-16

ERCC4 domain; This domain is a family of nucleases. The family includes EME1 which is an essential component of a Holliday junction resolvase. EME1 interacts with MUS81 to form a DNA structure-specific endonuclease.


Pssm-ID: 426945 [Multi-domain]  Cd Length: 139  Bit Score: 77.08  E-value: 2.14e-16
                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383  1040 TKGHKYQQDEYVLDFIVERKNVDDMRSSIMDNRYKDQKLRLQRsGIKKLIYILEGDP---------NQSKTAESIKTACF 1110
Cdd:pfam02732   35 VPREYDLELEVVLDVIVERKSLDDLVSSIIDGRLFEQKSRLKR-GYKKPILLVEGLDlfsrklknkRRDINPNAIEGALA 113
                           90
                   ....*....|....*....
gi 240256383  1111 TTEILEGFDVVRTNGLGET 1129
Cdd:pfam02732  114 SLQVDYGVRIIRTRSAEET 132
ERCC4 smart00891
ERCC4 domain; This entry represents a structural motif found in several DNA repair nucleases, ...
1010-1094 2.93e-15

ERCC4 domain; This entry represents a structural motif found in several DNA repair nucleases, such as Rad1/Mus81/XPF endonucleases, and in ATP-dependent helicases. The XPF/Rad1/Mus81-dependent nuclease family specifically cleaves branched structures generated during DNA repair, replication, and recombination, and is essential for maintaining genome stability. The nuclease domain architecture exhibits remarkable similarity to those of restriction endonucleases.


Pssm-ID: 214888 [Multi-domain]  Cd Length: 98  Bit Score: 72.38  E-value: 2.93e-15
                            10        20        30        40        50        60        70        80
                    ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383   1010 IPRLppLRFGEAFEEVYDViLILDDREQFATKGHKYQQDEYVLDFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLI 1089
Cdd:smart00891   17 IPRS--LRWKRGVKVEYDR-LEAGDFVLVARDKQSLLPHVNSLNELVERKSLTDLVASIPDGRLFEQVRRLQQIAYPSPQ 93

                    ....*
gi 240256383   1090 YILEG 1094
Cdd:smart00891   94 LLVEG 98
MUS81 COG1948
ERCC4-type crossover junction endonuclease [Replication, recombination and repair];
1050-1095 7.02e-05

ERCC4-type crossover junction endonuclease [Replication, recombination and repair];


Pssm-ID: 441551 [Multi-domain]  Cd Length: 214  Bit Score: 45.55  E-value: 7.02e-05
                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLIyILEGD 1095
Cdd:COG1948    36 YVVsdRVAVERKTVRDFVNSLIDGRLFEQASRLAEAYERPVL-IIEGD 82
PRK13766 PRK13766
Hef nuclease; Provisional
1050-1129 6.38e-03

Hef nuclease; Provisional


Pssm-ID: 237496 [Multi-domain]  Cd Length: 773  Bit Score: 41.01  E-value: 6.38e-03
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLIyILEGD--------PNqsktaeSIKTACFTTEILEGFD 1119
Cdd:PRK13766  597 YVVsdRVAVERKTAEDFVDSIIDRRLFEQVKDLKRAYERPVL-IIEGDlytirnihPN------AIRGALASIAVDFGIP 669
                          90
                  ....*....|
gi 240256383 1120 VVRTNGLGET 1129
Cdd:PRK13766  670 ILFTRDEEET 679
 
Name Accession Description Interval E-value
XPF_nuclease_Mus81 cd20074
XPF-like nuclease domain of Mus81; Mus81 is a crossover junction endonuclease that interacts ...
1026-1140 3.20e-39

XPF-like nuclease domain of Mus81; Mus81 is a crossover junction endonuclease that interacts with Eme1 and Eme2 to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. The typical substrates include 3'-flap structures, replication forks and nicked Holliday junctions. Mus81 may be required in mitosis for the processing of stalled or collapsed replication forks. Mus81 consists of the active nuclease domain with the GDX(n)ERKX(3)D motif which is required for metal-dependent endonuclease activity and two helix-hairpin-helix (HhH2) domains.


Pssm-ID: 410850 [Multi-domain]  Cd Length: 150  Bit Score: 143.01  E-value: 3.20e-39
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383 1026 YDVILILDDREQFATKGHKYQQD-------------------------------EYVLDFIVERKNVDDMRSSIMDNRYK 1074
Cdd:cd20074     2 YEVVLLVDNREVKGKKDRDYFQReleklgvkvetrslpvgdflwvarhksdtgeELVLDYIVERKRLDDLASSIKDGRYH 81
                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 240256383 1075 DQKLRLQRSGIKKLIYILEGDPNQSKT---AESIKTACFTTEILEGFDVVRTNGLGETLRKYGYLTKSI 1140
Cdd:cd20074    82 EQKFRLKRSGIKNVIYLVEGDGSAQSGglpEEALKTALANTQVVDGFFVKRTKSLDETVRYLARLTRAL 150
WH_MUS81 cd21036
winged helix domain found in crossover junction endonuclease MUS81 and similar proteins; MUS81 ...
838-939 1.83e-27

winged helix domain found in crossover junction endonuclease MUS81 and similar proteins; MUS81 is a crossover junction endonuclease that interacts with EME1 (essential meiotic structure-specific endonuclease 1) and EME2, to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. The MUS80-EME1 endonuclease maintains genomic integrity in metazoans by cleaving branched DNA structures that can form during mitosis and fission yeast meiosis, and during processing of damaged replication folks. This model corresponds to the winged helix (WH) domain of MUS81, which is responsible for DNA binding. It comprises four helices and two beta strands.


Pssm-ID: 411029  Cd Length: 94  Bit Score: 107.23  E-value: 1.83e-27
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383  838 YKPQRNTAAYA-LLTLHRFKTANGKKLMRKQKLMDAADASGLSHVSIApekgkgkaglgtSKREWYSGWSCMSKLIEKGL 916
Cdd:cd21036     1 YVPKYRSGAYAiLLALYKLDKEPGKGGLTKEELIRRAQPYCDSSFTIP------------DPGSFYTAWSSMKTLIKKGL 68
                          90       100
                  ....*....|....*....|...
gi 240256383  917 VVKFSNPAKYMLTVEGRNVADDL 939
Cdd:cd21036    69 VYKEGRPARYSLTEEGRELAEKL 91
XPF_ERCC4_MUS81-like cd22367
XPF family DNA repair endonuclease; (Xeroderma Pigmentosum group F) DNA repair gene homologs ...
1050-1137 7.11e-17

XPF family DNA repair endonuclease; (Xeroderma Pigmentosum group F) DNA repair gene homologs are members of the XPF/Rad1/Mus81-dependent nuclease family which specifically cleave branched structures generated during DNA repair, replication, and recombination, and they are essential for maintaining genome stability. They belong to a wider superfamily of nucleases including very short patch repair (Vsr) endonucleases, archaeal Holliday junction resolvases, MutH methyl-directed DNA mismatch-repair endonucleases, and catalytic domains of many restriction endonucleases, such as EcoRI, BamHI, and FokI.


Pssm-ID: 411771 [Multi-domain]  Cd Length: 123  Bit Score: 78.07  E-value: 7.11e-17
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGiKKLIYILEGDPNQSKTAES---IKTACFTTEILEGFDVVRTN 1124
Cdd:cd22367    33 YILsaDIIVERKTVSDLISSIIDGRLFEQAERLKRSY-ERPILLIEGDPDKARRLVRpaaLGAAISSLLVIGGLLVLRTP 111
                          90
                  ....*....|...
gi 240256383 1125 GLgETLRKYGYLT 1137
Cdd:cd22367   112 NF-ETTALLLSLL 123
ERCC4 pfam02732
ERCC4 domain; This domain is a family of nucleases. The family includes EME1 which is an ...
1040-1129 2.14e-16

ERCC4 domain; This domain is a family of nucleases. The family includes EME1 which is an essential component of a Holliday junction resolvase. EME1 interacts with MUS81 to form a DNA structure-specific endonuclease.


Pssm-ID: 426945 [Multi-domain]  Cd Length: 139  Bit Score: 77.08  E-value: 2.14e-16
                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383  1040 TKGHKYQQDEYVLDFIVERKNVDDMRSSIMDNRYKDQKLRLQRsGIKKLIYILEGDP---------NQSKTAESIKTACF 1110
Cdd:pfam02732   35 VPREYDLELEVVLDVIVERKSLDDLVSSIIDGRLFEQKSRLKR-GYKKPILLVEGLDlfsrklknkRRDINPNAIEGALA 113
                           90
                   ....*....|....*....
gi 240256383  1111 TTEILEGFDVVRTNGLGET 1129
Cdd:pfam02732  114 SLQVDYGVRIIRTRSAEET 132
ERCC4 smart00891
ERCC4 domain; This entry represents a structural motif found in several DNA repair nucleases, ...
1010-1094 2.93e-15

ERCC4 domain; This entry represents a structural motif found in several DNA repair nucleases, such as Rad1/Mus81/XPF endonucleases, and in ATP-dependent helicases. The XPF/Rad1/Mus81-dependent nuclease family specifically cleaves branched structures generated during DNA repair, replication, and recombination, and is essential for maintaining genome stability. The nuclease domain architecture exhibits remarkable similarity to those of restriction endonucleases.


Pssm-ID: 214888 [Multi-domain]  Cd Length: 98  Bit Score: 72.38  E-value: 2.93e-15
                            10        20        30        40        50        60        70        80
                    ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383   1010 IPRLppLRFGEAFEEVYDViLILDDREQFATKGHKYQQDEYVLDFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLI 1089
Cdd:smart00891   17 IPRS--LRWKRGVKVEYDR-LEAGDFVLVARDKQSLLPHVNSLNELVERKSLTDLVASIPDGRLFEQVRRLQQIAYPSPQ 93

                    ....*
gi 240256383   1090 YILEG 1094
Cdd:smart00891   94 LLVEG 98
XPF_nuclease_XPF_arch cd20075
nuclease domain of XPF found in archaea; XPF, also called DNA excision repair protein ERCC-4, ...
1050-1106 2.98e-07

nuclease domain of XPF found in archaea; XPF, also called DNA excision repair protein ERCC-4, or DNA repair protein complementing XP-F cells, or Xeroderma pigmentosum group F-complementing protein, is a 3'-flap repair endonuclease that cleaves 5' of ds/ssDNA interfaces in 3' flap structures, although it also cuts bubble, Y-DNA structures and mobile and immobile Holliday junctions. XPF cuts preferentially after pyrimidines, may continue to progressively cleave substrate upstream of the initial cleavage, at least in vitro. It may be involved in nucleotide excision repair. The nuclease domains of the catalytic subunits XPF have the GDX(n)ERKX(3)D motif which is required for metal-dependent endonuclease activity but not for DNA junction binding. XPF-ERRC1 and its yeast homolog Rad1-Rad10 play key roles in the excision of DNA lesions and are required for certain types of homologous recombination events and for the repair of DNA cross-links.


Pssm-ID: 410851 [Multi-domain]  Cd Length: 127  Bit Score: 50.46  E-value: 2.98e-07
                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLIyILEGDPNQSKTAESIK 1106
Cdd:cd20075    34 YIVsdRVAIERKTVDDFVSSIIDGRLFDQAKRLKEAYEKPIL-IIEGDLLYLKRRIHPN 91
XPF_nuclease-like cd19940
nuclease domain of XPF/MUS81 family proteins; The XPF/MUS81 family belongs to 3'-flap ...
1050-1123 2.03e-05

nuclease domain of XPF/MUS81 family proteins; The XPF/MUS81 family belongs to 3'-flap endonuclease that act upon 3'-flap structures and involved in DNA repair pathways that are necessary for the removal of UV-light-induced DNA lesions and cross-links between DNA strands. Family members exist either as heterodimers or as homodimers in their functionally competent states which consist of a catalytic and a noncatalytic subunit. The catalytic subunits have a DX(n)RKX(3)D motif. This motif is required for metal-dependent endonuclease activity but not for DNA junction binding. The equivalent regions of the noncatalytic subunits (ERCC1, EME1, and FAAP24) have diverged. The noncatalytic subunits have roles such as binding ssDNA or an ability to target the endonuclease to defined DNA structures or sites of DNA damage.


Pssm-ID: 410849 [Multi-domain]  Cd Length: 126  Bit Score: 45.45  E-value: 2.03e-05
                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGiKKLIYILEGDP---NQSKTAESIKTACFTTEILEGFDVVRT 1123
Cdd:cd19940    34 YVLsnRTCVERKSLSDLVSSINKGRLREQLQRLTRKF-ERRVLLVEKDRskfRSMVSSVQALSALTKLQLLTGIRLLIV 111
MUS81 COG1948
ERCC4-type crossover junction endonuclease [Replication, recombination and repair];
1050-1095 7.02e-05

ERCC4-type crossover junction endonuclease [Replication, recombination and repair];


Pssm-ID: 441551 [Multi-domain]  Cd Length: 214  Bit Score: 45.55  E-value: 7.02e-05
                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLIyILEGD 1095
Cdd:COG1948    36 YVVsdRVAVERKTVRDFVNSLIDGRLFEQASRLAEAYERPVL-IIEGD 82
PRK13766 PRK13766
Hef nuclease; Provisional
1050-1129 6.38e-03

Hef nuclease; Provisional


Pssm-ID: 237496 [Multi-domain]  Cd Length: 773  Bit Score: 41.01  E-value: 6.38e-03
                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 240256383 1050 YVL--DFIVERKNVDDMRSSIMDNRYKDQKLRLQRSGIKKLIyILEGD--------PNqsktaeSIKTACFTTEILEGFD 1119
Cdd:PRK13766  597 YVVsdRVAVERKTAEDFVDSIIDRRLFEQVKDLKRAYERPVL-IIEGDlytirnihPN------AIRGALASIAVDFGIP 669
                          90
                  ....*....|
gi 240256383 1120 VVRTNGLGET 1129
Cdd:PRK13766  670 ILFTRDEEET 679
 
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