[1] TERRA is RNA that is transcribed from telomeres — the repeating 6-nucleotide sequences that cap the ends of chromosomes.
TERRA functions with shelterin to inhibit telomere lengthening by enzyme telomerase.
[3][2] At least four factors contribute to telomere maintenance: telomerase, shelterin, TERRA and the CST Complex.
[4] TERRA can also regulate telomere length by increasing euchromatin formation.
[5] On the other hand, nonsense-mediated decay factor enrichment at telomeres may exist to prevent TERRA inhibition of telomerase.