TCEA1 is a member of the TFS-II family. TCEA1 binds to Pol II and operates to cleave the emerging transcript， thus unlocking the complex and permitting transcription to continue. TCEA1 is localized to the nucleus and holds three independently-folding domains that are essential for accurate binding to Pol II. The arresting sites in are able to trap a certain segment of elongating RNA polymerases that goes through， causing in a locked ternary complex. Cleavage of the emerging transcript by S-II enables the renewal of elongation from the new 3’-terminus.
