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

Abstract

We here describe the identification and characterization of a novel bromodomain‐containing protein, the bromodomain protein of 75 kDa (BP75). Initially, we identified BP75 in a two‐hybrid screening for proteins that interact with the first PDZ (acronym for post‐synaptic density protein PSD‐95, Drosophila discs large tumor suppressor DlgA and the tight junction protein ZO‐1) domain in protein tyrosine phosphatase‐BAS‐like (PTP‐BL). We found that BP75 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 nucleus, although cytoplasmic localization is also evident. Full‐length PTP‐BL, on 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 nuclear events.