Trans-activation response element

The HIV trans-activation response (TAR) element is an RNA element which is known to be required for the trans-activation of the viral promoter and for virus replication. The TAR hairpin is a dynamic structure^[1] that acts as a binding site for the Tat protein, and this interaction stimulates the activity of the long terminal repeat promoter.^[2]

Trans-activation response element (TAR)
Predicted secondary structure and sequence conservation of mir-TAR
Identifiers
Symbol	mir-TAR
Alt. Symbols	TAR
Rfam	RF00250
Other data
RNA type	Gene; miRNA
Domain(s)	Viruses
GO	GO:0035068 GO:0035195
SO	SO:0000233 SO:0001244
PDB structures	PDBe

Further analysis has shown that TAR is a pre-microRNA that produces mature microRNAs from both strands of the TAR stem-loop.^[3] These miRNAs are thought to prevent infected cells from undergoing apoptosis by downregulating the genes ERCC1, IER3,^[4] CDK9, and Bim.^[5]

Human polyomavirus 2 (JC virus) contains a TAR-homologous sequence in its late promoter^[6] that is responsive to HIV-1 derived Tat.^[7][8]