Cullin-RING ligase 4-Cereblon-Casein kinase 1 alpha neo-substrate interface (CRL4-CRBN-CK1α interface)

The CRL4-Cereblon E3 ligase complex – CK1α neo-substrate interface is a therapeutic target created by the binding of molecular glue degraders, most notably lenalidomide. In its native state, the Cereblon (CRBN) subunit of the CRL4 E3 ligase complex does not interact with Casein kinase 1 alpha (CK1α). However, the presence of specific immunomodulatory imide drugs (IMiDs) alters the surface of CRBN, creating a 'neo-interface' that high-affinity recruits CK1α for polyubiquitination and subsequent proteasomal degradation. This mechanism is particularly significant in the treatment of myelodysplastic syndrome (MDS) with isolated deletion of chromosome 5q. Patients with del(5q) MDS are haploinsufficient for the CSNK1A1 gene, which encodes CK1α, making them hypersensitive to further depletion of this kinase. The drug-induced degradation of the remaining CK1α protein triggers a p53-dependent apoptotic response that selectively eliminates the malignant clone. Beyond MDS, targeting this interface represents a landmark example of how small molecules can reprogram E3 ligases to target previously 'undruggable' proteins. Understanding the structural biology of this interface is critical for developing next-generation degraders with improved specificity and reduced off-target effects on other neo-substrates like Ikaros and Aiolos.

Other names

CRBN-CK1α interfaceCereblon-Casein kinase 1 alpha complexLenalidomide-induced CK1α degradation complexCRL4(CRBN)-CK1α interface

Molecular glue-induced recruitment of neo-substrate for ubiquitination and degradation