Mapping of the interaction sites of the growth suppressor protein p53 with the regulatory beta-subunit of protein kinase CK2.

p53 plays an essential role in cellular growth control. Some of its distinct biological functions are regulated by interaction with cellular proteins. We have previously (Wagner et al., 1994) shown that p53 binds to the regulatory subunit of protein kinase CK2. Using C-terminal protein fragments of p53 we now demonstrate that the region between amino acids 287 and 340 on the polypeptide chain of p53 is critical for binding of p53 to the beta-subunit of CK2. Neither phosphorylation at the p34cdc2 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 amino acids 72 and 149 of the beta-subunit of CK2 is necessary for binding to p53. Thus, this study defines new functional regions on the polypeptide chains of p53 and of protein kinase CK2.