Open AccessStructure and properties of casein kinase‐2 from Saccharomyces cerevisiae
Author(s) -
MEGGIO Flavio,
GRANKOWSKI Nikodem,
KUDLICKI Wieslaw,
SZYSZKA Ryszard,
GASIOR Eugeniusz,
PINNA Lorenzo A.
Publication year - 1986
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1986.tb09829.x
Subject(s) - casein kinase 2 , biochemistry , casein kinase 1 , protein subunit , casein kinase 2, alpha 1 , chemistry , saccharomyces cerevisiae , kinase , peptide , casein , dithiothreitol , polylysine , proteolysis , protein quaternary structure , autophosphorylation , phosphorylation , protein kinase a , microbiology and biotechnology , enzyme , yeast , biology , mitogen activated protein kinase kinase , gene
A type‐2 casein kinase (YCK‐2), lacking the 25‐kDa autophosphorylatable β subunit characteristic of animal casein kinases‐2, has been obtained in a nearly pure form from Saccharomyces cerevisiae and was compared with liver casein kinase‐2 (LCK‐2). A 22‐kDa phosphorylatable protein, copurifying with YCK‐2, can be removed by ultracentrifugation at low ionic strength and is shown by several criteria to be unrelated to the β subunit of LCK‐2. The native M r of YCK‐2, deprived of the 22‐kDa phosphoprotein, is about 150000. Limited proteolysis experiments show that YCK‐2 included 37‐kDa catalytic subunits, which can be converted into still active 35‐kDa proteolytic derivatives. These data are consistent with a homotetrameric quaternary structure as opposed to the heterotetrameric subunit composition α 2 β 2 of LCK‐2 and other animal casein kinases‐2. Although many properties of YCK‐2 and LCK‐2, including substrate specificity, inhibition by heparin, polyglutamic acid and quercetin and stimulation by polyamines, are similar; their stability under denaturating and dissociating conditions and their response to polybasic peptides are quite different. In particular YCK‐2 is more readily denaturated than LCK‐2 by heating and exposure to urea, sodium dodecylsulphate and deoxycholate while its activity is inhibited by 100–150 mM NaCl, which conversely stimulates LCK‐2 activity 2–3‐fold. The K m value of the synthetic peptide substrate Ser‐(Glu) 5 for YCK‐2 is not significantly changed by the addition of polylysine. On the contrary the K m value of the same peptide substrate for LCK‐2 decreases approximately tenfold upon addition of polylysine, which also prevents the fast autophosphorylation of the kinase at its β subunit. These data suggest that the β subunit of animal CK‐2 may play a role in determining both the stability of the enzyme and its regulation and that, consequently, the different properties of YCK‐2 may be at least in part accounted for by its lack of β subunits.