Purification and characterization of echinoderm casein kinase II. Regulation by protein kinase C

Abstract

Casein kinase II (CKII) is one of several protein kinases that become activated before germinal-vesicle breakdown in maturing sea-star oocytes. Echinoderm CKII was purified over 11000-fold with a recovery of -10% by sequential fractionation of the oocyte cytosol on tyrosine-agarose, heparin-agarose, casein-agarose and MonoQ. The purified enzyme contained 45, 38 and 28 kDa polypeptides, which corresponded to its a, c' and , subunits respectively. The ,3-subunit was autophosphorylated on one major tryptic peptide on serine residues, whereas the a'-subunit incorporated phosphate into at least two tryptic peptides primarily on threonine residues. Western-blotting analysis of sea-star oocyte extracts with two different anti-peptide antibodies that recognized conserved regions of the a-subunit indicated that the protein levels of the a-and a'-subunits of CKII were unchanged during oocyte maturation. The purified CKII was partly inactivated (by 25 %) by preincubation with protein-serine/threonine phosphatase 2A, but protein-tyrosine phosphatases had no effect. The f-subunit of CKII was phosphorylated on a serine residue(s) up to 0.54 mol of P/mol of fl-subunit by purified protein kinase C, and this correlated with a 1.5-fold enhancement of its phosphotransferase activity with phosvitin as a substrate. CKII was not a substrate for the maturation-activated myelin basic protein kinase p44mpk from sea-star oocytes, nor for cyclic-AMP-dependent protein kinase. These studies point to possible regulation of CKII by protein phosphorylation.

Casein Kinase II-Type Protein Kinase from Pea Cytoplasm and Its Inactivation by Alkaline Phosphatase in Vitro

“…The CK I1 kinases themselves are substrates for phosphorylation by ~34'~'' (Litchfield et al, 1992) and protein kinase C (Sanghera et al, 1992). The M-phase-specific ~3 4 '~'~ protein kinase can phosphorylate the p subunit of CK I1 and increase its activity (Mulner-Lorillon et al, 1990), and when epidermal growth factor stimulates CK I1 activity, it apparently does so by stimulating an increase in its phosphorylation state (Ackerman et al, 1990).…”

Phospholipase D is activated and phosphorylated by casein kinase-II in human U87 astroglioma cells

“…It has been suggested that CKII might have potentially important roles in neuronal function such as neuronal differentiation and proliferation (Blanquet, 2000). It was demonstrated that PKC stimulation via phorbol ester treatment increases CKII activity (Sanghera et al, 1992;Silva-Neto et al, 2002). PKC is also known to stimulate PLD activity (Frohman and Morris, 1999).…”

Heterogeneous expression of four MAP kinase isoforms in human tissues

“…kinase mRNAs suggests that different isoforms may play tissue-specific roles. Thus MAP kinases have been implicated in the M phase of the meiotic cycle [6,8,9], in the G0-to-Gl progression of quiescent cells [7,8,10], and may play a role in the differentiation of PC-12 cells [50,51]. Human tissues are physiologically regulated by a variety of extracellular factors that may employ a diversity of signal transduetion pathways.…”

“…Members of this family of kinases have been implicated in a wide variety of cellular processes. MAP kinases are activated during the M phase of the meiotic cycle [6,8,9] and during mitogenic stimulation of quiescent cells [7,8,10]. It has been shown that MAP kinases can induce reorganization of microtubules in vitro [11], and also may modulate Myc- [12] and Jun-[I 3] mediated activation of eerie expression.…”

“…Mitogen-activated protein kinases (MAP kinases) form a family of protein kinases that are activated by numerous extracellular stimuli in many cell types [1][2][3][4][5][6][7]. Members of this family of kinases have been implicated in a wide variety of cellular processes.…”