Protection Of Telomeres Protein 1 (POT1) C-terminal region; POT1 is part of shelterin, a hexameric nucleoprotein complex (comprising TRF1, TRF2, TIN2, RAP1, POT1 and TPP1 in humans) that protects telomeres, the physical ends of chromosomes. Shelterin protects against these ends being recognized as double-stranded DNA breaks, as well as against degradation of the telomeric overhang by endonucleases. It also helps control access of telomerase to the telomeric overhang, thereby affecting telomore length. This C-terminal region has an OB-fold domain and a holiday junction resolvase (HJR) domain which make dimer contacts with TPP1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 477 LEKTPLCAILKQKAPQQYRIRAKLRSYKPRRLFQSVKLHCPKCHSLQEVPHEGDLDIILQEGATKTPdaklqnTLLYDSK 556
Cdd:cd20374     1 LEQTPLSEVKKSTPPQQYHVRAKLRSYQPQRLYQSVKLFCPKCKSLQEVPDEEALANIFQEAATDSP------TSWYSSE 74

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 557 MWTTKD-----QGERKIAIHFVKNNgILPLSNDCLILIEGGTVDEIYKLSSKFHSVIPVKSGHEDLELVNLSAPFLIQGK 631
Cdd:cd20374    75 VWTLTGsldsgQGGRKVAVHFVKNM-MLQSPEKELIFIEGGTLEEICKLSKKFKNIIPVRSSEEDLTLLDLSAPFLFQGK 153

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 632 IHHYGCKQCSNLRPIQSLNSLVDKTQWIPSSVAEVLGIMPLQHVFVMTFTLDDGTGVLEAYL-MDSEKFFQIPASEILRN 710
Cdd:cd20374   154 KRYYGCKQCSSPKSIENLSSLVEKESWDESSVAEALGIQLLQYVFLMKFTLDDGTGTLEALLwLDAEKFFQISASEVLTD 233

                         250       260
                  ....*....|....*....|....*.
gi 1926215693 711 DDLQQNMDMIMDMFCPLGLKIGIRVW 736
Cdd:cd20374   234 QELQEKIQMIMDTLCPPGISIDERPW 259

Telomeric single stranded DNA binding POT1/CDC13; The telomere-binding protein forms a heterodimer in ciliates consisting of an alpha and a beta subunit. This complex may function as a protective cap for the single-stranded telomeric overhang. Alpha subunit consists of 3 structural domains, all with the same beta-barrel OB fold.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693  142 YTPLNQLKSG--MIVNVYGVVKFFKPPYVSKGTDYCSVVTIVDQTNVK---LTCLFFSGNYEALPIIYKNGDIVRFHRLK 216
Cdd:smart00976   1 FTPIKDLTSAtnKYVNVIGVVVDFKPPKRSRGTDFTCTLTITDPSYADgygLTVKLFSPTLESLPVIKYVGDIILLHRVK 80

                           90       100       110       120       130
                   ....*....|....*....|....*....|....*....|....*....|....*..
gi 1926215693  217 IQVYKNETQGITSSGFASLTFEGTLGALIIPRTSSKYFNFTTEDHKM-VEALRVWAS 272
Cdd:smart00976  81 IQDFNNRIQGLCSFGTSSWAVFGPLNGVVRERESSPPSTFTPEDEKQyVEELRNWAF 137

Protection Of Telomeres Protein 1 (POT1) C-terminal region; POT1 is part of shelterin, a hexameric nucleoprotein complex (comprising TRF1, TRF2, TIN2, RAP1, POT1 and TPP1 in humans) that protects telomeres, the physical ends of chromosomes. Shelterin protects against these ends being recognized as double-stranded DNA breaks, as well as against degradation of the telomeric overhang by endonucleases. It also helps control access of telomerase to the telomeric overhang, thereby affecting telomore length. This C-terminal region has an OB-fold domain and a holiday junction resolvase (HJR) domain which make dimer contacts with TPP1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 477 LEKTPLCAILKQKAPQQYRIRAKLRSYKPRRLFQSVKLHCPKCHSLQEVPHEGDLDIILQEGATKTPdaklqnTLLYDSK 556
Cdd:cd20374     1 LEQTPLSEVKKSTPPQQYHVRAKLRSYQPQRLYQSVKLFCPKCKSLQEVPDEEALANIFQEAATDSP------TSWYSSE 74

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 557 MWTTKD-----QGERKIAIHFVKNNgILPLSNDCLILIEGGTVDEIYKLSSKFHSVIPVKSGHEDLELVNLSAPFLIQGK 631
Cdd:cd20374    75 VWTLTGsldsgQGGRKVAVHFVKNM-MLQSPEKELIFIEGGTLEEICKLSKKFKNIIPVRSSEEDLTLLDLSAPFLFQGK 153

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 632 IHHYGCKQCSNLRPIQSLNSLVDKTQWIPSSVAEVLGIMPLQHVFVMTFTLDDGTGVLEAYL-MDSEKFFQIPASEILRN 710
Cdd:cd20374   154 KRYYGCKQCSSPKSIENLSSLVEKESWDESSVAEALGIQLLQYVFLMKFTLDDGTGTLEALLwLDAEKFFQISASEVLTD 233

                         250       260
                  ....*....|....*....|....*.
gi 1926215693 711 DDLQQNMDMIMDMFCPLGLKIGIRVW 736
Cdd:cd20374   234 QELQEKIQMIMDTLCPPGISIDERPW 259

hPOT1_OB2: A subfamily of OB folds similar to the second OB fold (OB2) of human protection of telomeres 1 protein (hPOT1). POT1 proteins bind to the single-stranded (ss) 3-prime ends of the telomere. hPOT1 binds specifically to ss telomeric DNA repeats ending with the sequence GGTTAG. The hPOT1 monomer consists of two closely connected OB folds (OB1-OB2) which cooperate to bind telomeric ssDNA. OB1 makes more extensive contact with the ssDNA than OB2. OB2 protects the 3' end of the ssDNA. hPOT1 is implicated in telomere length regulation.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 292 YFDLTCQLLGKAEVDGTSFLLKVWDGTRTPFPSWRVLIQDL-ALEGDLSHINRLQN---LTIDILVYDNHVQVAKSLKVG 367
Cdd:cd04498     1 YFDLLCQLLSVVETDSSSTLLKVWDGTKFPPPLRKVKVEDDvVLEGDRSLKHREEGgkqLTIDILVYDNHVELAKSLKPG 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....
gi 1926215693 368 SFLRIYSLHTKLQSVNSEtQATLLALEFHL-HGGTSYGRGIRVL 410
Cdd:cd04498    81 DFVRIYNVHAKSYSSKNE-HDENDHLHFHLvHGGTEYGRGIRVL 123

hPOT1_OB1_like: A subfamily of OB folds similar to the first OB fold (OB1) of human protection of telomeres 1 protein (hPOT1), the single OB fold of the N-terminal domain of Schizosaccharomyces pombe POT1 (SpPOT1), and the first OB fold of the N-terminal domain of the alpha subunit (OB1Nalpha) of Oxytricha nova telomere end binding protein (OnTEBP). POT1 proteins recognize single-stranded (ss) 3-prime ends of the telomere. A 3-prime ss overhang is conserved in ciliated protozoa, yeast, and mammals. SpPOT1 is essential for telomere maintenance. It binds specifically to the ss G-rich telomeric sequence (GGTTAC) of S. pombe. hPOT1 binds specifically to ss telomeric DNA repeats ending with the sequence GGTTAG. Deletion of the S. pombe pot1+ gene results in a rapid loss of telomere sequences, chromosome mis-segregation and chromosome circularization. hPOT1 is implicated in telomere length regulation. The hPOT1 monomer consists of two closely connected OB folds (OB1-OB2) which cooperate to bind telomeric ssDNA. OB1 makes more extensive contact with the ssDNA than OB2. OB2 protects the 3' end of the ssDNA. A second OB fold has not been predicted in S. pombe POT1. OnTEBP binds the extreme 3-prime end of telomeric DNA. It is heterodimeric and contains four OB folds - three in the alpha subunit (two in the N-terminal domain and one in the C-terminal domain) and one in the beta subunit. OB1Nalpha, together with the second OB fold of the N-terminal domain of OnTEBP alpha subunit and the beta subunit OB fold, forms a deep cleft that binds ssDNA.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 140 YIYTPLNQLK--SGMIVNVYGVVKFFKPPYVSKGTDYCSVVTIVDQT---NVKLTCLFFSGNYEALPIIyKNGDIVRFHR 214
Cdd:cd04497     1 YKYTPLSSALkeSGGSVNVIGVVVDAGPPVRSKGTDYCCTLTITDPSlanSDGLTVKLFRPNEESLPIV-KVGDIILLRR 79

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1926215693 215 LKIQVYKNETQGITS-SGFASLTFEGTLGALIIPRTSSKYFNFTTEDHKMVEALRVWAS 272
Cdd:cd04497    80 VKIQSYNGKPQGISNdRGSSWAVFRGDDGVVPIPQQSSKPVEFGPEEEPSVEELRKWAS 138

Protection Of Telomeres Protein 1 (POT1) C-terminal region; POT1 is part of shelterin, a hexameric nucleoprotein complex (comprising TRF1, TRF2, TIN2, RAP1, POT1 and TPP1 in humans) that protects telomeres, the physical ends of chromosomes. Shelterin protects against these ends being recognized as double-stranded DNA breaks, as well as against degradation of the telomeric overhang by endonucleases. It also helps control access of telomerase to the telomeric overhang, thereby affecting telomore length. This C-terminal region has an OB-fold domain and a holiday junction resolvase (HJR) domain which make dimer contacts with TPP1.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 477 LEKTPLCAILKQKAPQQYRIRAKLRSYKPRRLFQSVKLHCPKCHSLQEVPHEGDLDIILQEGATKTPdaklqnTLLYDSK 556
Cdd:cd20374     1 LEQTPLSEVKKSTPPQQYHVRAKLRSYQPQRLYQSVKLFCPKCKSLQEVPDEEALANIFQEAATDSP------TSWYSSE 74

                          90       100       110       120       130       140       150       160
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 557 MWTTKD-----QGERKIAIHFVKNNgILPLSNDCLILIEGGTVDEIYKLSSKFHSVIPVKSGHEDLELVNLSAPFLIQGK 631
Cdd:cd20374    75 VWTLTGsldsgQGGRKVAVHFVKNM-MLQSPEKELIFIEGGTLEEICKLSKKFKNIIPVRSSEEDLTLLDLSAPFLFQGK 153

                         170       180       190       200       210       220       230       240
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 632 IHHYGCKQCSNLRPIQSLNSLVDKTQWIPSSVAEVLGIMPLQHVFVMTFTLDDGTGVLEAYL-MDSEKFFQIPASEILRN 710
Cdd:cd20374   154 KRYYGCKQCSSPKSIENLSSLVEKESWDESSVAEALGIQLLQYVFLMKFTLDDGTGTLEALLwLDAEKFFQISASEVLTD 233

                         250       260
                  ....*....|....*....|....*.
gi 1926215693 711 DDLQQNMDMIMDMFCPLGLKIGIRVW 736
Cdd:cd20374   234 QELQEKIQMIMDTLCPPGISIDERPW 259

hPOT1_OB2: A subfamily of OB folds similar to the second OB fold (OB2) of human protection of telomeres 1 protein (hPOT1). POT1 proteins bind to the single-stranded (ss) 3-prime ends of the telomere. hPOT1 binds specifically to ss telomeric DNA repeats ending with the sequence GGTTAG. The hPOT1 monomer consists of two closely connected OB folds (OB1-OB2) which cooperate to bind telomeric ssDNA. OB1 makes more extensive contact with the ssDNA than OB2. OB2 protects the 3' end of the ssDNA. hPOT1 is implicated in telomere length regulation.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 292 YFDLTCQLLGKAEVDGTSFLLKVWDGTRTPFPSWRVLIQDL-ALEGDLSHINRLQN---LTIDILVYDNHVQVAKSLKVG 367
Cdd:cd04498     1 YFDLLCQLLSVVETDSSSTLLKVWDGTKFPPPLRKVKVEDDvVLEGDRSLKHREEGgkqLTIDILVYDNHVELAKSLKPG 80

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....
gi 1926215693 368 SFLRIYSLHTKLQSVNSEtQATLLALEFHL-HGGTSYGRGIRVL 410
Cdd:cd04498    81 DFVRIYNVHAKSYSSKNE-HDENDHLHFHLvHGGTEYGRGIRVL 123

hPOT1_OB1_like: A subfamily of OB folds similar to the first OB fold (OB1) of human protection of telomeres 1 protein (hPOT1), the single OB fold of the N-terminal domain of Schizosaccharomyces pombe POT1 (SpPOT1), and the first OB fold of the N-terminal domain of the alpha subunit (OB1Nalpha) of Oxytricha nova telomere end binding protein (OnTEBP). POT1 proteins recognize single-stranded (ss) 3-prime ends of the telomere. A 3-prime ss overhang is conserved in ciliated protozoa, yeast, and mammals. SpPOT1 is essential for telomere maintenance. It binds specifically to the ss G-rich telomeric sequence (GGTTAC) of S. pombe. hPOT1 binds specifically to ss telomeric DNA repeats ending with the sequence GGTTAG. Deletion of the S. pombe pot1+ gene results in a rapid loss of telomere sequences, chromosome mis-segregation and chromosome circularization. hPOT1 is implicated in telomere length regulation. The hPOT1 monomer consists of two closely connected OB folds (OB1-OB2) which cooperate to bind telomeric ssDNA. OB1 makes more extensive contact with the ssDNA than OB2. OB2 protects the 3' end of the ssDNA. A second OB fold has not been predicted in S. pombe POT1. OnTEBP binds the extreme 3-prime end of telomeric DNA. It is heterodimeric and contains four OB folds - three in the alpha subunit (two in the N-terminal domain and one in the C-terminal domain) and one in the beta subunit. OB1Nalpha, together with the second OB fold of the N-terminal domain of OnTEBP alpha subunit and the beta subunit OB fold, forms a deep cleft that binds ssDNA.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1926215693 140 YIYTPLNQLK--SGMIVNVYGVVKFFKPPYVSKGTDYCSVVTIVDQT---NVKLTCLFFSGNYEALPIIyKNGDIVRFHR 214
Cdd:cd04497     1 YKYTPLSSALkeSGGSVNVIGVVVDAGPPVRSKGTDYCCTLTITDPSlanSDGLTVKLFRPNEESLPIV-KVGDIILLRR 79

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1926215693 215 LKIQVYKNETQGITS-SGFASLTFEGTLGALIIPRTSSKYFNFTTEDHKMVEALRVWAS 272
Cdd:cd04497    80 VKIQSYNGKPQGISNdRGSSWAVFRGDDGVVPIPQQSSKPVEFGPEEEPSVEELRKWAS 138

RPA2_OBF_family: A family of oligonucleotide binding (OB) folds with similarity to the OB fold of the single strand (ss) DNA-binding domain (DBD)-D of human RPA2 (also called RPA32). RPA2 is a subunit of Replication protein A (RPA). RPA is a nuclear ssDNA-binding protein (SSB) which appears to be involved in all aspects of DNA metabolism including replication, recombination, and repair. RPA also mediates specific interactions of various nuclear proteins. In animals, plants, and fungi, RPA is a heterotrimer with subunits of 70KDa (RPA1), 32kDa (RPA2), and 14 KDa (RPA3). RPA contains six OB folds, which are involved in ssDNA binding and in trimerization. The ssDNA binding mechanism is believed to be multistep and to involve conformational change. This family also includes OB folds similar to those found in Escherichia coli SSB, the wedge domain of E. coli RecG (a branched-DNA-specific helicase), E. coli ssDNA specific exodeoxyribonuclease VII large subunit, Pyrococcus abyssi DNA polymerase II (Pol II) small subunit, Sulfolobus solfataricus SSB, and Bacillus subtilis YhaM (a 3'-to-5'exoribonuclease). It also includes the OB folds of breast cancer susceptibility gene 2 protein (BRCA2), Oxytricha nova telomere end binding protein (TEBP), Saccharomyces cerevisiae telomere-binding protein (Cdc13), and human protection of telomeres 1 protein (POT1).

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1926215693 155 NVYGVVKFFKPPYVSKgtdYCSVVTIVDQTNVKLTCLFFSGNYEALPIIYKNGDIVRFHrLKIQVYKNETQGITSS 230
Cdd:cd03524     1 TIVGIVVAVEEIRTEG---KVLIFTLTDGTGGTIRVTLFGELAEELENLLKEGQVVYIK-GKVKKFRGRLQLIVES 72