ASPP (ankyrin-repeat-, SH3-domain- proline-rich-region protein) proteins (ASPP1, ASPP2 and iASPP) represent a new family of p53 binding proteins. ASPP1 and ASPP2 bind and enhance p53-mediated apoptosis. In contrast, iASPP functionally inactivates p53. ASPPs may also regulate p63- and p73-mediated apoptosis. Both ASPP1 and 2 directly interact with p53 and specifically enhance the apoptotic function of p53 by stimulating its DNA binding and transactivation function on promoters of pro-apoptotic genes, such as Bax and PIG-3. Not all cell cycle arrest genes are affected, such as p21. Interestingly, expression of ASPP is frequently down-regulated in human breast carcinomas expressing wild-type p53 but not mutant p53. Therefore, ASPP might regulate the tumor suppression function of p53 in vivo.
This affinity purified antibody was prepared from whole rabbit serum produced by repeated immunizations with a synthetic peptide corresponding to an internal sequence of human ASPP2.