By now, many mammalian CTD kinases, phosphorylating CTD in vitro or in vivo, have been revealed, whereas only three human CTD phosphatases: FCP1, SCP1 and UBLCP1 have been identifited yet.

• 目前已确定有多种哺乳动物CTD激酶可在体外或体内磷酸化CTD，但已知的人类CTD磷酸酶则只有FCP1、SCP1、UBCP1。