In the initiation or early elongation stage, TAF7 interacts with MED26 NTD and blocks LEC recruitment by MED26. In the transition from initiation to elongation, MED26 NTD is released from TAF7 and LEC is recruited to a subset of snRNA genes. After LEC is recruited by MED26, MED26 hands LEC to Pol II, and thereby LEC activates productive elongation of Pol II. Binding sites for the MED26 NTD on TAF7 and EAF family members are represented by black bars. N, MED26 NTD.