Tert

Developmental stage

Highest levels in midgestational stages, 9.5 dpc to 15.5 dpc.

Domain

The primer grip sequence in the RT domain is required for telomerase activity and for stable association with short telomeric primers.

The RNA-interacting domain 1 (RD1)/N-terminal extension (NTE) is required for interaction with the pseudoknot-template domain of each of TERC dimers. It contains anchor sites that bind primer nucleotides upstream of the RNA-DNA hybrid and is thus an essential determinant of repeat addition processivity (By similarity).

The RNA-interacting domain 2 (RD2) is essential for both interaction with the CR4-CR5 domain of TERC and for DNA synthesis.

Function

Telomerase is a ribonucleoprotein enzyme essential for the replication of chromosome termini in most eukaryotes. Active in progenitor and cancer cells. Inactive, or very low activity, in normal somatic cells. Catalytic component of the teleromerase holoenzyme complex whose main activity is the elongation of telomeres by acting as a reverse transcriptase that adds simple sequence repeats to chromosome ends by copying a template sequence within the RNA component of the enzyme. Catalyzes the RNA-dependent extension of 3'-chromosomal termini with the 6-nucleotide telomeric repeat unit, 5'-TTAGGG-3'. The catalytic cycle involves primer binding, primer extension and release of product once the template boundary has been reached or nascent product translocation followed by further extension. More active on substrates containing 2 or 3 telomeric repeats. Telomerase activity is regulated by a number of factors including telomerase complex-associated proteins, chaperones and polypeptide modifiers. Modulates Wnt signaling. Plays important roles in aging and antiapoptosis (By similarity).

Post-translational modifications

Phosphorylation at Tyr-697 under oxidative stress leads to translocation of TERT to the cytoplasm and reduces its antiapoptotic activity. Dephosphorylated by SHP2/PTPN11 leading to nuclear retention. Phosphorylation by the AKT pathway promotes nuclear location. Phosphorylation at the G2/M phase at Ser-447 by DYRK2 promotes ubiquitination by the EDVP complex and degradation (By similarity).

Ubiquitinated by the EDVP complex, a E3 ligase complex following phosphorylation at Ser-447 by DYRK2. Ubiquitinated leads to proteasomal degradation (By similarity).

Sequence Similarities

Belongs to the reverse transcriptase family. Telomerase subfamily.

Tissue Specificity

High activity in intestine, liver and testis, moderate in lung, very low in muscle, heart and brain.

Cellular localization

• Nucleus
• Nucleolus
• Nucleus
• Nucleoplasm
• Nucleus
• Chromosome
• Telomere
• Cytoplasm
• Nucleus
• PML body
• Shuttling between nuclear and cytoplasm depends on cell cycle, phosphorylation states, transformation and DNA damage. Diffuse localization in the nucleoplasm. Enriched in nucleoli of certain cell types. Translocated to the cytoplasm via nuclear pores in a CRM1/RAN-dependent manner involving oxidative stress-mediated phosphorylation at Tyr-697. Dephosphorylation at this site by SHP2 retains TERT in the nucleus. Translocated to the nucleus by phosphorylation by AKT (By similarity).

Alternative names

Telomerase reverse transcriptase, Telomerase catalytic subunit, Tert

Database links

swissprot:O70372 entrezGene:21752

Other research areas

• Epigenetics