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

The transcription coactivator and histone acetyltransferase CAMP response element-binding protein (CBP) has been demonstrated to accumulate in promyelocytic leukemia (PML) bodies. We show that this accumulation is cell type specific. 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 photobleaching, we demonstrate that CBP moves rapidly into and out of PML bodies. In contrast, Pml and Sp100 are relatively immobile in the nucleoplasm and within PML nuclear bodies. They possess the characteristics expected of proteins that would play a structural role in the integrity of these subnuclear domains. Our results are consistent with CBP being a dynamic component of PML bodies and that the steady-state level in these structures can be modulated by Pml.