References
PMID:9069260
Activated HRAS (GTP bound forn) is associated with the plasma membrane.
Inactive RAF1 is associated in the cytoplasm with YWHAB via S259 phosphorylation site and also binding site.
RAF1 has a RAS-binding Cysteine-rich domain (CRD) and an additional RAS-binding domain (RBD).
RAF1 binds activated HRAS via the RBD. This binding displaces YWHAB from Ser259 and unmasks the CRD.
YWHAB has been displaced from S259 may now bind its higher affinity S621 site.
This stabilises an OPEN RAF1 conformation that is catalytically active.
Active and open RAF1 binds to RAS via both CRD and RBD domains.