The termini of PRMT6 are required for the interaction with HIV-1 Tat. (A) Upper panel, scale representation of PRMT6 protein showing amino acid positions 1 and 375, the catalytic domain (gray), and the signature methyltransferase motifs (I, I′, II and III; black bars). Lower panel, scale representations of Myc epitope-tagged PRMT6 (Myc-PRMT6) protein and derivative domain deletion mutants. The numbers above each schema represent the amino acid boundaries of the domain deletions. The amino-terminal Myc epitope tag is represented as a vertical bar. (B) Interactions between FLAG epitope-tagged Tat (Tat-FLAG) and wild type or domain deleted Myc-PRMT6 as determined by immunoprecipitation. HeLa cells were transfected to express Tat-FLAG with either wild type Myc-PRMT6 (WT) or a domain deletion mutant of Myc-PRMT6. Immunoprecipitations were performed on lysates prepared from transfected cells using anti-FLAG agarose beads (αFLAG IP). Cell lysates (left panel) and immunoprecipitates (right panel) were western blotted using anti-Myc and anti-FLAG antibodies. Loading of cell lysates was normalized for equal amounts of co expressed Renilla luciferase in each sample. The Myc-PRMT6 domain deletion mutant designations are as in A. Data are representative of three independent experiments.