p300 and CBP: Partners for life and death

p300 and CBP are highly related nuclear proteins, which have been implicate d in transcriptional responses to disparate extracellular and intracellular signals. There are at least two very good reasons for which p300 and CBP h ave attracted the attention of the scientific world. First, they belong to an unique class of transcription co-activators possessing histone acetyltra nsferase activity and therefore have the potential to reveal basic aspects pertaining to regulation of chromatin structure. Second, p300 and CBP deliv er essential functions in virtually all known cellular programs, including the decision to grow, to differentiate, or to commit suicide by apoptosis. Consistent with the complexity of these processes, a multitude of intracell ular factors physically interact with p300 and CBP. Thus, the task of many investigations has been the understanding of how these proteins receive sig nals in the cells, what induces their recruitment in a given signal transdu ction pathway, and what determines the final outcome of their individual ac tivity. This review will focus on mechanistic and theoretical questions per taining to the mode of action of p300 and CBP posed by works performed in a nimal and in vitro model systems. (C) 1999 Wiley-Liss, Inc.