The objective of this application is to dissect the structure-function relationships of CREB binding protein, CBP. It is proposed to 1) characterize the domains of CBP which activate transcription; 2) characterize the structural domains within the activation domains of CBP; 3) identify the core transcriptional molecules which interact with CBP; and, 4) determine the domains within CBP which are required for E1A repression of CBP-mediated transcription.