Furthermore, preventing binding of F-box substrate receptors to Cul1 does not increase CAND1 binding.
As an F-box substrate receptor, βTrCP may provide the primary and specific interaction between Perforin-2 and the CRL.
The ability of the CRL to recognize its substrate, via a F-box substrate receptor, is often dependent upon substrate modification, such as phosphorylation.
Several prominent F-box substrate receptors of CRL1, such as Skp2, β-TrCP, Fbw7 and Fbxl3, were shown to play significant roles in cancer and other diseases [ 28].
The F-box substrate receptors β-TrCP1 and β-TrCP2 can form homo- and hetero-dimers via their the N-terminal regions [ 123].
Regeneration of an active SCF complex thus requires displacement of Cand1, neddylation and association with a new Skp1 F-Box Skp1 F-Boxcomplex (Wu et al, 2006).
Skp1 adaptors act to recruit different F-box substrate recognition proteins to Cullin1 scaffolding molecules, facilitating the formation of hundreds of different E3 ubiquitin ligases [ 68- 71].
Another research group used quantitative MS to show that CAND1 regulates the in vivo dynamics of CRL assembly via exchange of F-box substrate receptors [ 115].
At that point, a new FPP molecule binds, while the farnesylated protein remains bound, followed by product dissociation either prior to or concerted with binding of a new CaaX-box substrate protein.
The ability of Sgt1 to couple Hsp90 to the specific arm of SCF complexes, along with its competitive displacement by the cullin arm, suggests a clear chaperone role for Hsp90 Sgt1 in binding and stabilizing a Skp1 F-Box Skp1 F-Boxcomplex in the absubstratecomplexx1.
