Identification and molecular characterization of BP75, a novel bromodomain-containing protein

We here describe the identification and characterization of a novel bromodo main-containing protein, the bromodomain protein of 75 kDa (BP75), Initiall y, we identified BP75 in a two-hybrid screening for proteins that interact with the first PDZ (acronym for post-synaptic density protein PSD-95, Droso phila discs large tumor suppressor D1gA and the tight junction protein ZO-1 ) domain in protein tyrosine phosphatase-BAS-like (PTP-BL), We found that B P75 is expressed ubiquitously and show that both BP75 and a PTP-BL deletion mutant consisting of the first PDZ domain are located mainly in the nucleu s, although cytoplasmic localization is also evident. Full-length PTP-BL, o n the contrary, is predominantly localized in the cytoplasm, although some basal nuclear staining is observed. The described molecular interaction may reflect a mechanism of coupling submembraneous signalling events and nucle ar events. (C) 1999 Federation of European Biochemical Societies.