MAPPING OF THE INTERACTION SITES OF THE GROWTH SUPPRESSOR PROTEIN P53WITH THE REGULATORY BETA-SUBUNIT OF PROTEIN-KINASE CK2

p53 plays an essential role in cellular growth control. Some of its di stinct biological functions are regulated by interaction with cellular proteins. We have previously (Wagner et al., 1994) shown that p53 bin ds to the regulatory subunit of protein kinase CK2. Using C-terminal p rotein fragments of p53 we now demonstrate that the region between ami no acids 287 and 340 on the polypeptide chain of p53 is critical for b inding of p53 to the beta-subunit of CK2. Neither phosphorylation at t he p34(cdc2) site (aa315) nor at the CK2 site (aa392) is necessary for binding of p53 to the beta-subunit of CK2. Using deletion mutants of the beta-subunit of CK2 we also show that an internal region between a mino acids 72 and 149 of the beta-subunit of CK2 is necessary for bind ing to p53. Thus, this study defines new functional regions on the pol ypeptide chains of p53 and of protein kinase CK2.