The transcription coactivator CBP is a dynamic component of the promyelocytic leukemia nuclear body

The transcription coactivator and histone acetyltransferase CAMP response e lement-binding protein (CBP) has been demonstrated to accumulate in promyel ocytic leukemia (PML) bodies. We show that this accumulation is cell type s pecific. In cells where CBP does not normally accumulate in PML bodies, it can be induced to accumulate in PML bodies through overexpression of either CBP or Pml, but not Sp100. Using fluorescence recovery after photobleachin g, we demonstrate that CBP moves rapidly into and out of PML bodies. In con trast, Pml and Sp100 are relatively immobile in the nucleoplasm and within PML nuclear bodies. They possess the characteristics expected of proteins t hat would play a structural role in the integrity of these subnuclear domai ns. Our results are consistent with CBP being a dynamic component of PML bo dies and that the steady-state level in these structures can be modulated b y Pml.