InterPro domain: IPR034393

Tat-SF1 (HIV Tat-specific factor 1) interacts with components of both the transcription and splicing machineries [ 1 ]. It has been shown to be a cofactor for human immunodeficiency virus-type 1 (HIV-1) Tat, which stimulates transcription elongation of HIV-1 through a series of events termed Tat transactivation [ 2 , 3 ]. It contains two RNA recognition motifs (RRMs) and a highly acidic carboxyl-terminal half.

This entry also includes Cus2, a yeast homologue of human Tat-SF1. Cus2 interacts with U2 snRNA and Prp11, a subunit of the conserved splicing factor SF3a [ 4 ]. Like Tat-SF1, Cus2 contains two RRMs.

1. Identification of Tat-SF1 cellular targets by exon array analysis reveals dual roles in transcription and splicing. RNA 17, 665-74
2. Tat-SF1 is not required for Tat transactivation but does regulate the relative levels of unspliced and spliced HIV-1 RNAs. PLoS ONE 4, e5710
3. Stimulatory effect of splicing factors on transcriptional elongation. Nature 414, 929-33
4. CUS2, a yeast homolog of human Tat-SF1, rescues function of misfolded U2 through an unusual RNA recognition motif. Mol. Cell. Biol. 18, 5000-9