Fig. 3

SRSF7 interacts RNA-independently with FIP1 via its hypo-phosphorylated RS domain. a, b Co-immunoprecipitations (Co-IPs) using GFP-tagged cleavage factors FIP1 (a) and CPSF5 (b): proteins were pulled-down by α-GFP antibodies and probed for interaction partners using specific antibodies. Lysates were treated with (+RNase) or without (−RNase) RNase A prior to IPs. PABPN1 served as a control for RNA degradation. Inp, input; IP, immunoprecipitation; IgG, unspecific antibody control. c Scheme of tetracyclin repressor (TetR) protein fused to RS domains of SRSF3 (RS3), SRSF7 (RS7), or phosphomimetic (RD7) and non-phosphorylatable (RA7) versions of SRSF7. d, e Co-IPs for TetR using GFP-FIP1 (d) and CPSF5-GFP (e) cell lines: Proteins were pulled-down by α-GFP antibodies and probed for interaction with TetR-fusion proteins using α-TetR antibodies. RNase A treatment and loading control as in a. f Scheme of mCherry fused to the complete coding sequence of WT SRSF7[RS] or its variants SRSF7[RD]/[RA]. g, h Co-IPs using GFP-FIP1 (g) and CPSF5-GFP (h) cell lines: Proteins were pulled-down by α-GFP antibodies and probed for interaction with mCherry fusion proteins using an α-mCherry antibody. RNase A treatment and loading control as in (a)