The arginine-serine (RS) rich C-terminus as well as the RRMH domain of SRSF6 are dispensable for its antiviral activity. (A) SRSF6 protein variants used in the coexpression experiments. Proper expression of all truncated SRSF6 variants was confirmed using an antibody specifically recognizing an HA epitope (Sigma-Aldrich, H6908), which was C-terminally fused to each mutant. HEK293T cells were transiently cotransfected with 1 μg of pNL4-3 and 1 μg of pcDNA3.1(+) or the respective SRSF6 variant-expression plasmid. Samples from the same RNA preparations were analyzed by both RT-PCR (B) and Northern blot (C). (D) Cellular lysates and supernatants were analyzed by Western blot using antibodies directed against viral Gag or cellular actin (loading control). Values and error bars show the average ± standard deviation of two independent transfection experiments.