9SHY: Telomerase reverse transcriptase

Cryo-EM structure of the catalytic core of human telomerase at the initiation state of the repeat addition cycle. Determined by electron microscopy at 3.53 Å resolution. Released 28 Jan 2026.

Method: Electron microscopy
Resolution: 3.53 Å
Organism: Homo sapiens
Chains: 6
Atoms: 15,563
Mol. weight: 365.16 kDa
Ligands: 1GC
Released: 28 Jan 2026

Explore 9SHY in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9SHY contains 69 α-helices and 47 β-strands across 4 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 55 helices, 39 β-strands

Element	Residues	Length	Sheet
α-helix	8-15	8
β-strand	20-23	4	1
α-helix	24-31	8
α-helix	33	1
α-helix	45-53	9
β-strand	54-58	5	1
α-helix	77-90	14
α-helix	96-98	3
β-strand	101-102	2	2
β-strand	120-121	2	2
α-helix	126-133	8
α-helix	135-154	20
β-strand	157-161	5	1
β-strand	167-171	5	1
β-strand	325-327	3	3
α-helix	328-331	4
β-strand	332	1	4
α-helix	341-342	2
α-helix	346-349	4
α-helix	354-361	8
α-helix	362-366	5
α-helix	379-383	5
α-helix	384-387	4
α-helix	390-402	13
α-helix	405-412	8
α-helix	414-416	3
α-helix	445-452	8
β-strand	456	1	4
α-helix	458-472	15
α-helix	475-478	4
α-helix	481-495	15
β-strand	502-504	3	3
α-helix	505-508	4
α-helix	518-520	3
α-helix	531-547	17
α-helix	548-552	5
α-helix	553-560	8
β-strand	561-564	4	4
β-strand	574-577	4	4
α-helix	578-595	18
β-strand	598-600	3	5
α-helix	601-602	2
α-helix	603-611	9
β-strand	618-626	9	5
β-strand	629-636	8	5
α-helix	639-641	3
α-helix	649-652	4
α-helix	654-671	18
α-helix	673-676	4
β-strand	679	1	6
α-helix	683-697	15
α-helix	703-705	3
β-strand	707-712	6	6
β-strand	713	1	7
α-helix	722-732	11
β-strand	738	1	8
β-strand	739-749	11	1
β-strand	755-765	11	1
α-helix	773-783	11
β-strand	790-797	8	1
β-strand	801	1	8
α-helix	802-814	13
β-strand	817-820	4	5
β-strand	823-827	5	5
α-helix	838-853	16
α-helix	855-858	4
β-strand	862-866	5	6
β-strand	869-874	6	6
α-helix	877-888	12
β-strand	891	1	9
β-strand	896	1	9
β-strand	898	1	7
α-helix	900-902	3
β-strand	904-905	2	6
α-helix	912-914	3
α-helix	916-918	3
β-strand	920-921	2	6
β-strand	927-930	4	10
β-strand	933-936	4	10
β-strand	942-944	3	10
α-helix	946-949	4
β-strand	953	1	11
α-helix	954-957	4
α-helix	966-979	14
α-helix	984-987	4
α-helix	994-1016	23
α-helix	1025-1027	3
α-helix	1029-1049	21
β-strand	1058	1	12
β-strand	1062	1	12
α-helix	1067-1084	18
α-helix	1086-1106	21
α-helix	1109-1119	11
β-strand	1131	1	11

Chain L: 4 helices, 1 β-strand

Element	Residues	Length	Sheet
α-helix	29-37	9
α-helix	47-72	26
β-strand	78-79	2	13
α-helix	81-90	10
α-helix	92-98	7

Chain M: 4 helices, 1 β-strand

Element	Residues	Length	Sheet
α-helix	39-49	11
β-strand	54-55	2	13
α-helix	57-84	28
α-helix	92-102	11
α-helix	107-124	18

Chain O: 6 helices, 6 β-strands

Element	Residues	Length	Sheet
α-helix	99-103	5
β-strand	113-123	11	14
β-strand	142-147	6	14
β-strand	152-157	6	14
α-helix	159-163	5
α-helix	170-172	3
β-strand	180-190	11	14
β-strand	203-215	13	14
α-helix	217-219	3
β-strand	223	1	14
α-helix	224-226	3
α-helix	228-237	10

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Telomerase reverse transcriptase	A	protein	1132	Homo sapiens	O14746 (AlphaFold model)
Histone H2A	L	protein	130	Homo sapiens	B2R5B3 (AlphaFold model)
Histone H2B	M	protein	166	Homo sapiens	B4DR52 (AlphaFold model)
DNA (5'-d(ptptpapgpgpgptptpapg)-3')	N	DNA	34	Homo sapiens
Adrenocortical dysplasia protein homolog	O	protein	458	Homo sapiens	Q96AP0 (AlphaFold model)
hTR, human telomerase RNA	B	RNA	451	Homo sapiens

Sequence of entity 1 (A), FASTA

>9SHY_1 Telomerase reverse transcriptase (chains A)
MPRAPRCRAVRSLLRSHYREVLPLATFVRRLGPQGWRLVQRGDPAAFRALVAQCLVCVPW
DARPPPAAPSFRQVSCLKELVARVLQRLCERGAKNVLAFGFALLDGARGGPPEAFTTSVR
SYLPNTVTDALRGSGAWGLLLRRVGDDVLVHLLARCALFVLVAPSCAYQVCGPPLYQLGA
ATQARPPPHASGPRRRLGCERAWNHSVREAGVPLGLPAPGARRRGGSASRSLPLPKRPRR
GAAPEPERTPVGQGSWAHPGRTRGPSDRGFCVVSPARPAEEATSLEGALSGTRHSHPSVG
RQHHAGPPSTSRPPRPWDTPCPPVYAETKHFLYSSGDKEQLRPSFLLSSLRPSLTGARRL
VETIFLGSRPWMPGTPRRLPRLPQRYWQMRPLFLELLGNHAQCPYGVLLKTHCPLRAAVT
PAAGVCAREKPQGSVAAPEEEDTDPRRLVQLLRQHSSPWQVYGFVRACLRRLVPPGLWGS
RHNERRFLRNTKKFISLGKHAKLSLQELTWKMSVRDCAWLRRSPGVGCVPAAEHRLREEI
LAKFLHWLMSVYVVELLRSFFYVTETTFQKNRLFFYRKSVWSKLQSIGIRQHLKRVQLRE
LSEAEVRQHREARPALLTSRLRFIPKPDGLRPIVNMDYVVGARTFRREKRAERLTSRVKA
LFSVLNYERARRPGLLGASVLGLDDIHRAWRTFVLRVRAQDPPPELYFVKVDVTGAYDTI
PQDRLTEVIASIIKPQNTYCVRRYAVVQKAAHGHVRKAFKSHVSTLTDLQPYMRQFVAHL
QETSPLRDAVVIEQSSSLNEASSGLFDVFLRFMCHHAVRIRGKSYVQCQGIPQGSILSTL
LCSLCYGDMENKLFAGIRRDGLLLRLVDDFLLVTPHLTHAKTFLRTLVRGVPEYGCVVNL
RKTVVNFPVEDEALGGTAFVQMPAHGLFPWCGLLLDTRTLEVQSDYSSYARTSIRASLTF
NRGFKAGRNMRRKLFGVLRLKCHSLFLDLQVNSLQTVCTNIYKILLLQAYRFHACVLQLP
FHQQVWKNPTFFLRVISDTASLCYSILKAKNAGMSLGAKGAAGPLPSEAVQWLCHQAFLL
KLTRHRVTYVPLLGSLRTAQTQLSRKLPGTTLTALEAAANPALPSDFKTILD

Sequence of entity 2 (L), FASTA

>9SHY_2 Histone H2A (chains L)
MSGRGKQGGKARAKAKTRSSRAGLQFPVGRVRRLLRKGNYAERVGAGAPVYLAAVLEYLT
AEILELAGNAARDNKKTRIIPRHLQLAIRNDEELNKLLGKVTIAQGGVLPNIQAVLLPKK
TESHHKAKGK

Sequence of entity 3 (M), FASTA

>9SHY_3 Histone H2B (chains M)
MPDPAKSAPAPKKGSKKAVTKVQKKDGKKRKRSRKESYSVYVYKVLKQVHPDTGISSKAM
GIMNSFVNDIFERIAGEASRLAHYNKRSTITSREIQTAVRLLLPGELAKHAVSEGTKAVT
KYTSSNPRNLSPTKPGGSEDRQPPPSQLSAIPPFCLVLRAGIAGQV

Sequence of entity 4 (N), FASTA

>9SHY_4 DNA (5'-D(P*TP*TP*AP*GP*GP*GP*TP*TP*AP*G)-3') (chains N)
TTAGGGTTAGGGTTAGGGTTAGGGTTAGGGTTAG

Sequence of entity 5 (O), FASTA

>9SHY_5 Adrenocortical dysplasia protein homolog (chains O)
MAGSGRLVLRPWIRELILGSETPSSPRAGQLLEVLQDAEAAVAGPSHAPDTSDVGATLLV
SDGTHSVRCLVTREALDTSDWEEKEFGFRGTEGRLLLLQDCGVHVQVAEGGAPAEFYLQV
DRFSLLPTEQPRLRVPGCNQDLDVQKKLYDCLEEHLSESTSSNAGLSLSQLLDEMREDQE
HQGALVCLAESCLTLEGPCTAPPVTHWAASRCKATGEAVYTVPSSMLCISENDQLILSSL
GPCQRTQGPELPPPDPALQDLSLTLIASPPSSPSSSGTPALPGHMSSEESGTSISLLPAL
SLAAPDPGQRSSSQPSPAICSAPATLTPRSPHASRTPSSPLQSCTPSLSPRSHVPSPHQA
LVTRPQKPSLEFKEFVGLPCKNRPPFPRTGATRGAQEPCSVWEPPKRHRDGSAFQYEYEP
PCTSLCARVQAVRLPPQLMAWALHFLMDAQPGSEPTPM

Sequence of entity 6 (B), FASTA

>9SHY_6 hTR, human telomerase RNA (chains B)
GGGUUGCGGAGGGUGGGCCUGGGAGGGGUGGUGGCCAUUUUUUGUCUAACCCUAACUGAG
AAGGGCGUAGGCGCCGUGCUUUUGCUCCCCGCGCGCUGUUUUUCUCGCUGACUUUCAGCG
GGCGGAAAAGCCUCGGCCUGCCGCCUUCCACCGUUCAUUCUAGAGCAAACAAAAAAUGUC
AGCUGCUGGCCCGUUCGCCCCUCCCGGGGACCUGCGGCGGGUCGCCUGCCCAGCCCCCGA
ACCCCGCCUGGAGGCCGCGGUCGGCCCGGGGCUUCUCCGGAGGCACCCACUGCCACCGCG
AAGAGUUGGGCUCUGUCAGCCGCGGGUCUCUCGGGGGCGAGGGCGAGGUUCAGGCCUUUC
AGGCCGCAGGAAGAGGAACGGAGCGAGUCCCCGCGCGCGGCGCGAUUCCCUGAGCUGUGG
GACGUGCACCCAGGACUCGGCUCACACAUGC

Ligands and cofactors

ID	Name	Formula	Copies
1GC	2'-deoxy-5'-O-[(R)-hydroxy{[(S)-hydroxy(phosphonooxy)phosphoryl]methyl}phosphor…	C11 H18 N5 O12 P3	1

Primary citation

Structures of nucleotide-bound human telomerase at several steps of its telomeric DNA repeat addition cycle. Balch, S., Franco-Echevarria, E., Ghanim, G.E. et al. Nat Commun (2026) 17:1847-1847. DOI 10.1038/s41467-026-68560-8 · PubMed

Other PDB entries of the same protein (UniProt O14746 (AlphaFold model), which also has an AlphaFold model), best resolution first:

5MEO 1.77 Å, Human Leukocyte Antigen presenting ILGKFLHRL
5MER 1.88 Å, Human Leukocyte Antigen A02 presenting ILAKFLHEL
5MEQ 2.27 Å, Human Leukocyte Antigen A02 presenting ILAKFLHTL
5UGW 2.31 Å, Structure of the human telomerase thumb domain
4B18 2.52 Å, The crystal structure of human Importin alpha 5 with TERT NLS peptide
9Q16 2.7 Å, Human telomerase catalytic core with shelterin protein TPP1, dGpNHpp and DNA primer…
5MEP 2.71 Å, Human Leukocyte Antigen A02 presenting ILGKFLHWL
4MNQ 2.74 Å, TCR-peptide specificity overrides affinity enhancing TCR-MHC interactions
2BCK 2.8 Å, Crystal Structure of HLA-A*2402 Complexed with a telomerase peptide
9Q12 2.8 Å, Human telomerase catalytic core with shelterin protein TPP1 and DNA primer ending in TTAG
5MEN 2.81 Å, Human Leukocyte Antigen A02 presenting ILAKFLHWL, in complex with cognate T-Cell Receptor
9Q10 2.9 Å, Human telomerase catalytic core with shelterin protein TPP1, dTpNHpp and DNA primer…

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