The present invention relates to the TIP60-transcriptional activator protein complex, which is a part of the beta-amyloid precursor protein (APP) processing pathway, component proteins of the said complexes, fragments and derivatives of the component proteins, and antibodies specific to the complexes. The present invention also relates to methods for use of these complexes and the interacting proteins in, inter alia, screening, diagnosis, and therapy, as well as to methods of preparing the complexes.