telomeraz

Telomeraz, commonly known as telomerase, is a ribonucleoprotein enzyme that maintains telomeres—the repetitive DNA sequences at chromosome ends. By adding telomeric repeats to the 3' ends of linear chromosomes, telomeraz compensates for the DNA lost during replication and helps preserve genomic stability in cells that divide repeatedly, such as stem cells, germ cells, and certain rapidly proliferating somatic cells.

The enzyme consists of a catalytic protein subunit, telomerase reverse transcriptase (TERT), and an essential RNA component that provides the telomere template (TERC in humans). Additional associated proteins, including dyskerin (DKC1) and other factors, stabilize the complex and aid in the assembly of the active ribonucleoprotein. The RNA template directs the addition of telomeric repeats (TTAGGG in humans) by reverse transcription, extending the 3' end of telomeres.

Telomeraz activity is tightly regulated. It is high in embryonic stem cells, germ cells, and some somatic cells with high proliferative demand, and it is typically repressed in most adult tissues, where telomeres shorten with each cell division. Reactivation or upregulation of telomeraz is a feature of many cancers, contributing to cellular immortality. Mutations in TERT or TERC can cause telomere-related disorders, such as dyskeratosis congenita, highlighting the enzyme’s role in genome maintenance. Therapeutically, telomerase inhibitors are being explored in cancer treatment, while research continues into controlled modulation of telomerase for aging or regenerative purposes.