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Protein p21 WAF1/CIP1 is phosphorylated by protein kinase CK2 in vitro and interacts with the amino terminal end of the CK2 beta subunit
Author(s) -
RomeroOliva Francisco,
Allende Jorge E.
Publication year - 2001
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/1097-4644(20010601)81:3<445::aid-jcb1058>3.0.co;2-2
Subject(s) - casein kinase 2 , casein kinase 1 , casein kinase 2, alpha 1 , phosphorylation , kinase , protein subunit , biochemistry , biology , microbiology and biotechnology , protein kinase a , cyclin dependent kinase 2 , cyclin dependent kinase , cell cycle , cell , gene
Protein kinase CK2 is a ubiquitous protein that phosphorylates multiple substrates and is composed of catalytic (α, α′) and regulatory (β) subunits. Abundant evidence relates CK2 to the regulation of cell division. p21 WAF1/CIP1 is a potent inhibitor of cyclin‐dependent kinases and of DNA replication and acts as a key inhibitor of cell cycle progression. In this work we examine the relation between these two important proteins. The interaction between the CK2β regulatory subunit of CK2 and p21 WAF1/CIP1 has been confirmed. Using a pull‐down assay and fusion constructs of glutathione transferase with fragments of CK2β and other mutants, it was possible to define that the N‐terminal (1‐44) portion of CK2β contains a p21 WAF1/CIP1 binding site. CK2 reconstituted from recombinant α and β subunits can phosphorylate p21 WAF1/CIP1 in vitro. This phosphorylation is greatly enhanced by histone H1. p21 WAF1/CIP1 can inhibit the phosphorylation of substrate casein by CK2. This inhibition, however, seems to be due to competition by p21 WAF1/CIP1 as an alternate substrate since in order to observe inhibition it is necessary that the concentration of p21 be of the same order of magnitude as the casein substrate concentration. This competition is not related to the binding of p21 WAF1/CIP1 to CK2β because it can also be observed when, in the absence of CKβ, CKα is used to phosphorylate casein in the presence of the p21. J. Cell. Biochem. 81:445–452, 2001. © 2001 Wiley‐Liss, Inc.