The Molecules of HIV

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TAR

An article from "The Molecules of HIV" (c) Dan Stowell
www.mcld.co.uk/hiv

The HIV protein tat is necessary for the transcription of HIV DNA, for the simple reason that without it, the "trans-activating response region" or TAR mucks things up.

The TAR is found in the Long Terminal Repeat of HIV RNA/DNA. It's present in all mRNA transcripts and prevents the efficient use of the mRNA. tat binds to the RNA version of TAR and cancels its effect, allowing the mRNA to be efficiently processed into protein.

The TAR regions of HIV-1 and HIV-2 are different (HIV-1 TAR is pictured below) - but the conserved CUGGGA loop (at the top of the diagram), as well as the bulge just a little way down from that, has been shown to be essential for the trans-activation response.

More information:

Position in genome: just at the start of the genome, after the 3' LTR.
HIV can be inhibited experimentally by using TAR-RNA decoys

Written by
Dan Stowell
(©2002-2006)