Pathway Human Homo sapiens

Telomere Extension By Telomerase

R-HSA-171319 in Reactome release 97: under Extension of Telomeres, with 23 genes placed in it by the mapping files and 0 child pathways in the hierarchy.

The same number in the other species

Reactome writes the mouse and rat events it infers from a human pathway under the human number with the species token. A door opens only where that species' own list in this release holds the id: R-MMU-171319 (mouse), R-RNO-171319 (rat). Whether the event was inferred from this one is what the record says.

The record
The genes
Parents and children

Scripts are off

This page reads the pathway's record from its source while you read the rest; with scripts off the card stays at its loading line. Reload with scripts on to see it, or open the source's own page from the link in the card.

01The record

Reactome's own record of this pathway

What this tells you

The pathway list, the hierarchy and the genes on this page are read from the files Reactome publishes for Reactome release 97, built into this site on 2026-09-09: the pathway list, the hierarchy relationship file and the two gene mapping files. The record card is the one live read, Reactome's own record of this pathway.

Reactome's download page describes the mapping files: Mapping files link the source database identifier to the lowest level pathway diagram or subset of the pathway, all levels of the pathway hierarchy or database identifier to all reactions. [R13] The gene list here is the all-levels mapping of NCBI Gene ids, filled from the all-levels mapping of Ensembl ids where the NCBI file has no row for a gene; each row names which file it came from by the shape of its source id. Each row carries the evidence codes the file writes for it, as written and unranked, and both where the file writes both; no page of Reactome's documentation the survey read defines the codes, so this page does not expand them. A gene id the identity files do not name is kept as the source's own id with no door rather than turned into a symbol.

On citing what a search finds, Reactome says: It should be remembered that while we strive to contain the most current and accurate data, Reactome should not be used in citations where other primary sources of information are available. [R12] The record card prints the literature Reactome attaches to a curated pathway for that reason. The data are public domain: All data in the Reactome database and files derived from that data are licensed under the Creative Commons Public Domain Dedication (CC0). User may copy, modify, and distribute these data, even for commercial purposes, without asking for permission. Attribution is encouraged but not required. [R10] The pathway illustrations are licensed apart, under CC BY 4.0, and none is shown here.

A gene on this list is one Reactome places in this pathway in this release, and that is all the row says: it does not say the gene is expressed in a tissue or associated with a disease, which are the other two explorers' questions, read from other sources. Reactome's papers of record are [R01] [R02].

[R01] Ragueneau E, Gong C, Sinquin P, Sevilla C, Beavers D, Grentner A, et al. (2026). The Reactome Knowledgebase 2026. Nucleic Acids Research 54:D673-D681. PMID 41251150, doi 10.1093/nar/gkaf1223.
[R02] Milacic M, Beavers D, Conley P, Gong C, Gillespie M, Griss J, et al. (2024). The Reactome Pathway Knowledgebase 2024. Nucleic Acids Research 52:D672-D678. PMID 37941124, doi 10.1093/nar/gkad1025.
[R10] Reactome, reactome.org. License Agreement. https://reactome.org/license, read 2026-09-09.
[R12] Reactome, reactome.org. Citing us. https://reactome.org/cite, read 2026-09-09.
[R13] Reactome, reactome.org. Download. https://reactome.org/download-data, read 2026-09-09.

Stable id: R-HSA-171319.5
Class: Pathway
Species: Homo sapiens (human)
Inferred: no: a curated human pathway
Disease pathway: no
Released: 2006-08-02
Last updated: 2020-06-17
Events inside: 10, counted from the record

Humans, like most eukaryotic organisms, add direct repeats to the telomere using a specialized DNA polymerase called telomerase. Telomerase is a ribonucleoprotein (RNP) complex minimally composed of a conserved protein subunit containing a reverse transcriptase domain (human telomerase reverse transcriptase, hTERT) and a template-containing RNA (human telomerase RNA component, hTERC, or hTR, hTER). The primer for telomerase is the G-rich single-strand overhang at the chromosome end.

Telomerase can perform multiple rounds of repeat synthesis. The reaction cycle has been inferred from in vitro studies of telomerase from multiple organisms and can be described as having four events: 1) DNA primer recognition, 2) RNA template alignment, 3) elongation, and 4) translocation. Telomeric DNA is recognized in part by a presumed "anchor site" in hTERT, which preferentially binds G-rich DNA, and this interaction can affect elongation and translocation steps. This interaction occurs 5' of the alignment of the RNA template with the end nucleotides of the chromosome. RNA alignment positions the template adjacent to the chromosome terminus. During elongation, the template directs sequential addition of nucleotides to the telomere end. After synthesis of a repeat is completed, relative movement of telomerase and the primer, termed translocation, repositions telomerase at the end of the newly added sequence to allow initiation of another round of repeat addition.

Literature Reactome attaches

Regulation of telomerase by telomeric proteinsAnnu Rev Biochem, 2004, vol. 73, p. 177-208PubMed 15189140
Getting to the end: telomerase access in yeast and humansNat Rev Mol Cell Biol, 2003, vol. 4, p. 948-59PubMed 14685173

Reactome's record lists 13 orthologous events, R-RNO-171319 (Rattus norvegicus), R-MMU-171319 (Mus musculus) among the species this site serves, and 11 in species this site opens no page for.

Reactome ContentService, this pathway's record · Reactome v97 · read 2026-10-01 ET · Reactome pathway browser"Telomere Extension By Telomerase". Reactome, release 97, https://reactome.org/PathwayBrowser/#/R-HSA-171319 with StableID: R-HSA-171319.5 (accessed 2026-10-01 ET). Reactome version 97 (CC0).

Reading this pathway's record from Reactome (the pathway record).Still reading. A first read of a pathway can take a while; this page waits up to 35 seconds for it, and its scripts then bring in the panel, or a line saying what did not arrive.

02The genes

Genes Reactome places in this human pathway

The mapping files place 23 genes in this human pathway; showing 1 to 23, in pages of 100, sorted by symbol for reading. The order carries no ranking.

Genes Reactome places in this human pathway, page 1 of 1
Gene	Authority id	Mapping file id	Evidence codes
GeneACD	AuthorityHGNC:25070	Mapping file id65057 NCBI file	EvidenceTAS
GeneANKRD28	AuthorityHGNC:29024	Mapping file id23243 NCBI file	EvidenceTAS
GeneCCNA1	AuthorityHGNC:1577	Mapping file id8900 NCBI file	EvidenceTAS
GeneCCNA2	AuthorityHGNC:1578	Mapping file id890 NCBI file	EvidenceTAS
GeneCDK2	AuthorityHGNC:1771	Mapping file id1017 NCBI file	EvidenceTAS
GeneDKC1	AuthorityHGNC:2890	Mapping file id1736 NCBI file	EvidenceTAS
GeneGAR1	AuthorityHGNC:14264	Mapping file id54433 NCBI file	EvidenceTAS
GeneNHP2	AuthorityHGNC:14377	Mapping file id55651 NCBI file	EvidenceTAS
GeneNOP10	AuthorityHGNC:14378	Mapping file id55505 NCBI file	EvidenceTAS
GenePIF1	AuthorityHGNC:26220	Mapping file id80119 NCBI file	EvidenceTAS
GenePOT1	AuthorityHGNC:17284	Mapping file id25913 NCBI file	EvidenceTAS
GenePPP6C	AuthorityHGNC:9323	Mapping file id5537 NCBI file	EvidenceTAS
GenePPP6R3	AuthorityHGNC:1173	Mapping file id55291 NCBI file	EvidenceTAS
GeneRTEL1	AuthorityHGNC:15888	Mapping file id51750 NCBI file	EvidenceTAS
GeneRUVBL1	AuthorityHGNC:10474	Mapping file id8607 NCBI file	EvidenceTAS
GeneRUVBL2	AuthorityHGNC:10475	Mapping file id10856 NCBI file	EvidenceTAS
GeneSHQ1	AuthorityHGNC:25543	Mapping file id55164 NCBI file	EvidenceTAS
GeneTERF1	AuthorityHGNC:11728	Mapping file id7013 NCBI file	EvidenceTAS
GeneTERF2	AuthorityHGNC:11729	Mapping file id7014 NCBI file	EvidenceTAS
GeneTERF2IP	AuthorityHGNC:19246	Mapping file id54386 NCBI file	EvidenceTAS
GeneTERT	AuthorityHGNC:11730	Mapping file id7015 NCBI file	EvidenceTAS
GeneTINF2	AuthorityHGNC:11824	Mapping file id26277 NCBI file	EvidenceTAS
GeneWRAP53	AuthorityHGNC:25522	Mapping file id55135 NCBI file	EvidenceTAS

Evidence codes on this page: TAS, as the mapping file writes them; a row carrying two was written twice by the file, once under each. The mapping file id says which file placed the gene: an NCBI Gene id from NCBI2Reactome_All_Levels.txt, an Ensembl gene id from Ensembl2Reactome_All_Levels.txt. The two files can disagree about a code, so a row's codes are the one file's view. Measured by this site's build over this release on 2026-09-09: of the 138,908 human pathway-gene pairs both files place, 207 (0.149 per cent, over 47 genes) carry TAS in the Ensembl file where the NCBI rows carry IEA alone.

Reactome mapping files, the human rows for this pathway · Reactome release 97 · read 2026-09-09 · Reactome downloads"NCBI2Reactome_All_Levels.txt" and "Ensembl2Reactome_All_Levels.txt", Reactome, release 97, https://reactome.org/download-data/ (date of access 2026-09-09). Data CC0; attribution encouraged.

03The hierarchy

Parents and children in this release's hierarchy

Parents

Extension of TelomeresR-HSA-18078651 genes

Children

None: no pathway of this release's list names this one as a parent.

Reactome's hierarchy is a graph rather than a tree: a pathway can sit under more than one parent, and the gene counts are each pathway's own placements at every level under it, so a parent's count is not the sum of its children's.

Reactome, the human pathway list and hierarchy relationship file · Reactome release 97 · read 2026-09-09 · Reactome downloads"ReactomePathways.txt" and "ReactomePathwaysRelation.txt", Reactome, release 97, https://reactome.org/download-data/ (date of access 2026-09-09). Data CC0; attribution encouraged.