TELOMERASE

Discovered by Carol Greider and Liz Blackburn in 1985, telomerase is a unique ribonucleoprotein (RNP) enzyme that adds telomeric repeats to the 3' end of chromosomes to counteract the DNA degradation that occurs due to the end replication problem. The Telomerase RNP contains two essential core components, the telomerase reverse transcriptase (TERT) and the telomerase RNA (TR), along with other species-specific telomerase associated proteins. The TR component contains a template region that is complementary to the telomeric DNA sequence, while TERT contains the catalytic reverse transcriptase domain responsible for nucleotide addition. The TERT and TR components are sufficient to reconstitute activity in vitro, however a variety of species-specific proteins are necessary for telomerase function in vivo and are thus thought to be involved in the regulation and biogenesis of telomerase. Telomerase is active in immortal cells such as germline and stem cells. Telomerase activity is also..