Table S1.

Protein expression vectors

Constructs	Protein residues†	Vector	N terminus	Tag residues‡
Bacterial vectors
Fbw7 (F-box–WD40)	263–708	pPROEX HTb	His-TEV	MSYYHHHHHHDYDIPTT ENLYF*QGA
Fbw7 F-box	263–367
Fbw7 F-box (Structure)	263–323
Fbw2 F-box	53–104
Fbw5 F-box	1–79
Fbl1 F-box	95–139
Fbw12 F-box	1–49
Fbw1 F-box	101–214
Fbw11 F-box	80–191
Skp1	Full length	pPROEX HTb	GST-TEV	GST-DYDIPTTENLYFQ*GA
Skp1 (Loop 1Δ)	38–43Δ
Skp1 (Loop 2Δ)	70–77Δ,
	K78G E79S K80G R81G
Skp1tr (ELISA/structure)	38–43Δ, 70–77Δ,
	K78G E79S K80G R81G
Cul1 NTD§	1–410	P11	His-TEV-FLAG	MGSSHHHHHHSSGRENLYFQ*GHMDYKDDDDK
	(V367D L371E)
Ubv.Fw7.1 (structure)	1–76	p53DEST	His-TEV	MAHHHHHHVTSLYKKAG ENLYFQ*GSGS
Ubv (ELISA)	Full length	p53DEST	His-FLAG	MAHHHHHHVTSLYKKAG DYKDDDDK
Mammalian vectors
FLAG-Ubv monomer	Full length	pcDNA3.1/	FLAG-Linker-FLAG	MDYKDDDKGQGPDPSTNSADITSLYKKAGTMDYKDDDDK
		nFLAGDEST
FLAG-Ubv	Full length	pcDNA3.1/	FLAG-	MDYKDDDKGQ RMKQLEDKIEELLSKIYHLENEIARLKKLIGERTSLYKKAGTMDYKDDDDK
Leu-zipper dimer		nFLAGDEST(+Leu-zipper)	Leu Zipper-FLAG
HA-Fbw7	Full length	pcDNA3.1/	HA	MYPYDVPDYAGQG PDPSTNSADITSLYKKAGST
HA-Fbw11 (Isoform B)		nHADEST
FLAG-Cul1	Full length	pcDNA3.1/	FLAG	MDYKDDDDKGQGPDPSTNSADITSLYKKAGT
FLAG-Fbw7		nFLAGDEST
FLAG-Fbw11(isoform B)
FLAG-Fbw1	Full length	pcDNA3	FLAG	MDYKDDDDK

^†Residue limits of canonical human isoforms. Any amino acid substitutions relative to WT are indicated if present.

^‡Tag residues are shown, except for GST tag. Residues that comprise functional elements are underlined and TEV cleavage site denoted by an asterisk. All tags are N-terminal.

^§Cul1 NTD was expressed with V367D and L371E substitutions that are necessary for solubility in the absence of the C-terminal domain as described previously (16).