Matrin 3 interacts with Rev in the presence of viral Rev-dependent RRE-containing RNA. A) Schematic representations of the RNAs expressed from the various p37Gag constructs. B) Co-immunoprecipitation of GFP-Rev occurs only in the context of p37-RRE. HeLa cells were transfected with either pCMV-HA (lanes 1-6), or pCMVHA-Matrin 3 (lane 7-12) and GFP-Rev (lanes 1-12) plasmids, along with the indicated versions of a p37Gag expression construct (see panel A and as indicated). Cell lysates were subjected to immunoprecipitation with anti-HA antibody. Western blot analysis of co-immunoprecipitations shows that interaction occurs between Rev and Matrin 3 in the presence of co-transfected p37RRE (lane 8, top panel) construct, but not p37, p37CTE, or codon optimized P37 Gag constructs that are Rev-independent (lanes 7 and 9-12, top panel). Lower two panels show the expression of Rev and Matrin 3 in cell lysates used for the immunoprecipitations, and the second panel from the top shows HA-Matrin 3 proteins recovered by the co-immunoprecipitations.