Figure 3.

SET2 associates with the elongating, CTD phosphorylated, RPO21. (A) Total cell extracts from the N-terminal tagged TAP-SET2 or SIF2-TAP strains were either directly used (input) or affinity purified (purified) before electrophoresis and blotting. The blots were probed with antibodies detecting unphosphorylated (8WG16, Covance) and serine 5 phosphorylated (CTD4H8, Upstate) RPO21. Ponceau staining of the same blots showing the RPO21 bands on both membranes. (B) As for (A) except that C-terminal tagged SET2 was used from either a wild-type background or a Δssn3 background as indicated. Also, parallel blots were probed with antibodies against RPO21, whether phosphorylated or not, (ARNA3a, Research Diagnostics), serine 2 phosphorylated (H14, Covance) and serine 5 phosphorylated (H5, Covance) RPO21.