Telomerase is the enzyme required for the addition of telomeric repeats to the ends of linear chromosomes. It consists of a reverse transcriptase, TERT, that carries its own template in the form of an RNA moiety, TER. In vitro this complex can add telomeric repeats to artificial substrates.

Why is telomerase a reverse transcriptase?

The human telomerase reverse-transcriptase (TERT) gene encodes a rate-limiting catalytic subunit of telomerase, which maintains the length of telomeric DNA and chromosomal stability. Thus, TERT plays a pivotal role in cellular immortalization, cancer development and progression.

Is telomerase a DNA polymerase?

Telomerase is an RNA-directed DNA polymerase, or reverse transcriptase (17, 35), that uses its RNA component as a template for the addition of new telomeric sequences onto chromosome ends. ... Many reports suggest that alterations in chromatin structure at telomeres can also affect telomere length equilibrium.