Tar RNA Binding Protein 2 (TARBP2)

TARBP2, encoding a 345-amino acid protein termed TRBP by the authors. Mutation analysis showed that the TARBP2 protein binds to the helix between the bulge and the loop of the TAR RNA. Functional analysis demonstrated that TARBP2 enhanced expression of the HIV-1 LTR 20- to 60-fold and that the transactivation required an intact TAR RNA structure.

TARBP2 encodes 90- and 37-kD proteins in mouse cells, a 37-kD protein in hamster cells, and a 55-kD protein in monkey and human cells. TARBP2binds between the bulge and the loop of the HIV-1 TAR RNA regulatory element and activates HIV-1 gene expression in synergy with the viral Tat protein. Alternative splicing results in multiple transcript variants encoding different isoforms.