TBB is one of the most selective protein kinase inhibitors known, and when tested against a panel of 33 serine/threonine and tyrosine protein kinases, only three exhibited moderate inhibition by TBB, with Ki values one to two orders of magnitude higher than that for CK2.
A cell-permeable, selective inhibitor of casein kinase-2 (CK2) (IC 50 = 0.9 and 1.6 μ M for rat liver and human recombinant CK2 respectively). Exhibits modest discrimination between CK2 subunits, with K i values ranging from 80 nM to 210 nM. Acts in an ATP/GTP-competitive manner and displays one to two orders of magnitude selectivity over a panel of 33 protein kinases.
TBB binds to the Val66 residue of casein kinase-2 and inhibits the binding of ATP/GTP. TBB is cell permeable; it induces caspase-dependent apoptosis and degrades hematopoietic lineage cell-specific protein 1 in Jurkat cells.
