Matrin 3 promotes the expression of Rev dependent RRE containing transcripts. A) HeLa cells were transfected with Matrin 3 and Tat along with HIV-1 LTR luciferase. Luciferase assays performed on cell lysates prepared from these cells did not show any effect of Matrin 3 on Tat dependent LTR transactivation. B) Matrin 3 enhances the expression of RRE containing RNA transcripts in the presence of Rev in HeLa cells. HeLa cells were transfected with 2.0 μg of Matrin 3 expression or control plasmid along with 0.5 μg of pCMV -GagPol-RRE plasmids in the presence or absence of Rev. HA-Matrin 3 significantly increased the expression of Gag from the reporter construct pCMV-GagPol-RRE in the presence of Rev (compare lanes 2 and 4). C) Gag expression from CTE containing pCMV-GagPol-CTE reporter was not effected by HA-Matrin 3 (compare lanes 5 and 6).