Table 1.

Competitive Binding Assays and Conditions

Assay	BCL6BTB a	Co-repressor	Reference
ELISA	FLAG-BCL6BTB	Biotinylated BCOR peptideb	38, 42, 50
TR-FRET	His tagged BCL6BTBc	Hilyte647 SMRT peptided	60, 91
	Biotinylated BCL6BTB	TAMRA-peptide 4e	72
	Biotinylated BCL6BTB	FITC-BCOR peptidef	83
	Trx-His tagged BCL6BTBg	AF633-BCOR peptideh	95
	Avi-tag biotinylated BCL6BTBi	BCOR ULight peptidej	69
	GST-BCL6BTBk	His tagged SMRT peptidel	70
FP	Avi-tag biotinylated BCL6BTBi	FP-labeled BCOR peptidem	69
	BCL6BTB	AF633-BCOR peptideh	95
AlphaLisa	His tagged BCL6BTB c	Biotinylated BCOR peptideb	73
IPC	Avi-tag biotinylated BCL6BTBi	37 (BCL6-FP)	78

^aBCL6^BTB (5-129)

^bBiotinylated BCOR peptide = Ac-RSEIISTAPSSWVVPGP-Lys-(ε-Biotin-(AC₅)₂)-OH

^cHis tagged BCL6^BTB = Histidine (His) tagged BCL6^BTB (5-129) triple mutant (C8Q, C67R, and C84N)

^dHilyte™ Fluor 647 SMRT peptide H1426W = Hilyte™ Fluor 647-LVATVKEAGRSIWEIPR

^eTAMRA peptide 4 = TAMRA-Abu(4)-VWYTDIRMRDWM-OH

^fFITC, fluorescein isothiocyanate (Note: In the paper, BodipyFL-labeled BCOR peptide, but in SI FITC-BCOR peptide)

^gTrx, Thioredoxin

^hAlexa Fluor 633-BCOR peptide = Ac-RSEIISTAPSSWVVPGP-Cys-Alexa Fluor 633-CONH₂

ⁱAvi-tag, amino acid sequence GLNDIFEAQKIEWHE

^jBCOR ULight peptide = Ac-RSEIISTAPSSWVVPGP-Cys-ULight

^kGST, Glutathione S-transferase

^lHis tagged SMRT peptide = H6-LVATVKEAGRSIHEIPR

^mFP-labeled BCOR peptide = 5-TAMRA-RSEIISTAPSSWVVPGP