KI-DX-014 is a specific small-molecule compound capable of inhibiting the interaction of DDX21 with RNA with IC50 of 3.31 uM, directly binds to DDX21-C-terminal domain (HC+CTD) with Kd of 15.9 uM, allosterically attenuates DDX21 ATPase activity.
KI-DX-014 inhibits DDX21's C-terminal domain interaction with RNA.
KI-DX-014 does not impair the ability of the DDX21 to unwind an RNA duplex, shows no inhibitory activity against U15 binding
KI-DX-014 specifically inhibits the binding of structured RNAs, such as 7SK-SL1 and 7SK-SL4, which interact with the CTD of DDX21.
KI-DX-014 does not inhibit the unwinding activity of DDX21 or its binding to nonstructured RNAs.
KI-DX-014 affects the ability of DDX21 to undergo phase separation in vitro.
KI-DX-014 blocks DDX21-dependnet release of P-TEFb from the 7SK snRNP in vitro and Pol II phosphorylation in vivo.
KI-DX-014 suppresses DDX21-dependent phosphorylation of the Pol II CTD by inhibiting P-TEFb release, leading to developmental defects in zebrafish embryos.
DDX21 is a member of the DEAD-box protein family, capable of binding and remodeling RNA structures and RNA–protein complexes through ATP hydrolysis.