TERRA (biology)

TERRA in biology is an abbreviation for "TElomeric Repeat-containing RNA". 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 telomerase enzyme. At least four factors contribute to telomere maintenance: telomerase, shelterin, TERRA and the CST Complex.

TERRA can also regulate telomere length by increasing euchromatin formation. On the other hand, nonsense-mediated decay factor enrichment at telomeres may exist to prevent TERRA inhibition of telomerase. TERRA levels vary during the cell cycle, decreasing during S phase, and increasing in the transition from G2 phase to G1 phase.