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Telomerase is a reverse transcriptase enzyme that carries its own RNA molecule (e.g., with the sequence 3′-CCCAAUCCC-5′ in Trypanosoma brucei) [3] which is used as a template when it elongates telomeres. Telomerase is active in gametes and most cancer cells, but is normally absent in most somatic cells.
Human chromosomes (grey) capped by telomeres (white). A telomere (/ ˈ t ɛ l ə m ɪər, ˈ t iː l ə-/; from Ancient Greek τέλος (télos) 'end' and μέρος (méros) 'part') is a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes (see Sequences).
In most multicellular eukaryotic organisms, telomerase is active only in germ cells, some types of stem cells such as embryonic stem cells, and certain white blood cells. [9] Telomerase can be reactivated and telomeres restored to the embryonic state by somatic cell nuclear transfer. [18]
Two concerns with applying telomerase inhibitors in cancer treatment are that effective treatment requires continuous, long-term drug application and that off-target effects are common. [30] For example, the telomerase inhibitor imetelstat, first proposed in 2003, [31] [32] has been held up in clinical trials due to hematological toxicity. [30]
This single-stranded DNA structure can act as an origin of replication that recruits telomerase. Telomerase is a specialized DNA polymerase that consists of multiple protein subunits and an RNA component. The RNA component of telomerase anneals to the single stranded 3' end of the template DNA and contains 1.5 copies of the telomeric sequence. [93]
Alternative Lengthening of Telomeres (also known as "ALT") is a telomerase-independent mechanism by which cancer cells avoid the degradation of telomeres.. At each end of the chromosomes of most eukaryotic cells, there is a telomere: a region of repetitive nucleotide sequences which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes.
US life expectancy has rebounded closer to pre-pandemic levels. Deidre McPhillips, CNN. December 19, 2024 at 12:01 AM. People born in 2023 are now estimated to live 78.4 years, according to the CDC.
Telomerase is a ribonucleoprotein polymerase that maintains telomere ends by addition of the telomere repeat TTAGGG. The enzyme consists of a protein component with reverse transcriptase activity, encoded by this gene, and an RNA component that serves as a template for the telomere repeat.