PFI-4 A chemical probe for BRPF1B

This probe is available from Sigma, Tocris and Cayman.

group new

Overview

BRPF1/2/3 are scaffolding proteins assembling HAT complexes of the MOZ/MORF family transcriptional coactivators (MOZ, Ybf2/Sas3, Sas2 and Tip60). BRPF1 links the catalytic HATs to the other subunits ING5 and hEAF6. Translocations of MOZ are associated with aggressive subtypes of leukemia, producing, for example, the MOZ-TIF2 fusion protein, which also interacts with BRPF1. BRPF1 is important for maintaining Hox gene expression and skeletal development in fish.

BRPF1 exists in 2 different isoforms: BRPF1A and BRPF1B. A residue insertion in the ZA loop of BRPF1A prevents binding to acetylated histone peptides. BRPF1A may act as dominant negative isoform of BRPF1 generated by alternative splicing.

A chemical probe for the bromodomains of the BRPF1B has been developed in collaboration with Pfizer. PFI-4 specifically binds to BRPF1B with a Kd =13 nM as determined by ITC. It reduces recovery time in U2OS cells transfected with a BRPF1B triple BRD construct with a nuclear localisation signal (NLS) in the FRAP assay at 500nM, while showing no effect on BRPF1A. A cellular target engagement assay evaluating the interaction of BRPF1B with histones suggested and EC50 of 250 nM for PFI-4.

Properties

Physical and chemical properties
Molecular weight	380.45
Molecular formula	C₂₁H₂₄N₄O₃
IUPAC name	N-(1,3-dimethyl-2-oxo-6-(pyrrolidin-1-yl)-2,3-dihydro-1H-benzo[d]imidazol-5-yl)-2-methoxybenzamide
clogP	2.23
PSA	65.12
No. of chiral centres	0
No. of rotatable bonds	5
No. of hydrogen bond acceptors	4
No. of hydrogen bond donors	1
Storage	Stable as solid in the dark at -20°C. NB making aliquots rather than freeze-thawing is recommended
Dissolution	Soluble in DMSO