Remodeling And Spacing Factor 1 (RSF1)

HBXAP is involved in transcription repression, transcription coactivation when associated with hepatitis B virus X protein (HBX), and chromatin remodeling and spacing when associated with SNF2H. It contains a PHD finger and 2 nuclear localization signals. RNA dot blot analysis of 50 different tissues detected ubiquitous expression of HBXAP, with highest expression in adrenal and pituitary glands, and lowest expression in skeletal muscle. SDS-PAGE indicated that in vitro translated HBXAP had an apparent molecular mass of about 240 kD. Western blot analysis detected endogenous HBXAP in 3 liver-derived cell lines. Endogenous HBXAP and epitope-tagged HBXAP expressed in COS-1 cells localized in nuclei, with no staining in the cytoplasm and nucleolar structures.