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Mapping the residues of protein kinase CK2 α subunit responsible for responsiveness to polyanionic inhibitors
Author(s) -
Vaglio Philippe,
Sarno Stefania,
Marin Oriano,
Meggio Flavio,
Issinger Olaf-G.,
Pinna Lorenzo A.
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01542-6
Subject(s) - protein subunit , chemistry , biochemistry , protein kinase a , kinase , gene
The quadruple mutation of the whole basic cluster, K 74 KKK 77 conserved in the catalytic subunits of protein kinase CK2 and implicated in substrate recognition, not only abolishes inhibition by heparin but even induces with some peptide substrates an up to 5‐fold stimulation by heparin in the 0.5–5 μg/ml concentration range. Two other mutants defective in substrate recognition, R191,195K198A and K79R80K83A, display either a 100‐fold reduction or no alteration at all in heparin inhibition, respectively. In contrast sensitivity to heparin inhibition is increased 30‐fold by a single mutation affecting Arg‐228 while it is not altered by a triple mutation in the small insert of subdomain XI (mutant R278K279R280A). The effect of the same mutations on inhibition by pseudosubstrate Y is different, the mutant displaying the most reduced sensitivity being R191,195K198A, followed by K74‐77A and K79R80K83A; the other mutants are almost indistinguishable from CK2 wild type. Substantial reduction of inhibition by poly(Glu,Tyr)4:1 is only observable with mutant R191,195K198A, whereas R228A is significantly more sensitive to inhibition. These data show that the mode of inhibition of CK2 by polyanionic compounds occurs through substantially different mechanisms involving residues that are variably concerned with substrate recognition.