Figure 2.

Phase separation in promoter-proximal pause and release. RNA Pol II and its regulatory factors can form dynamic phase-separated condensates within cells, regulating transcription. P-TEFb can be extracted from the inactive 7SK/HEXIM1 complex by the SEC core component ENL via LLPS, and thus is incorporated into the SEC droplets to activate transcription. Unblending of transcriptional condensates via the expansion of amino acid repeats in HOXD13 may cause the disease synpolydactyly. Mutations of SEC components, such as fusion with MLL in leukemia and mutations of the ENL YEATS in Wilms tumor, increase the capability of SEC to phase-separate.