Extended Data Fig. 6: The UBR boxes of UBR4 present substrates towards the interior of SIFI.
From: Molecular basis of SIFI activity in the integrated stress response
a. The UBR box of UBR4 binds to DOC1 domain of UBR4 and the N-terminal domain of KCMF1, forming the KCMF1N138-DOC1-UBR subcomplex. X-ray structure of the UBR box of UBR1 (PDB 3NIH)35 reveals that its peptide binding groove is open. b. Modelling a N-degron peptide into the open substrate-binding groove of the UBR box of UBR4, based on the UBR1 X-ray structure (PDB 3NIH). c. Structure of SIFI showing the proximity of UBR box to other substrate-binding modules of SIFI, including the DOC2 domain of UBR4 and the ZZ domain of KCMF1.
