Possible Interaction: Caseins and Heparin

“Study of inhibition mechanism reveals that heparin acts as a non competitive inhibitor with respect to both substrates: ATP and casein.”

“Nuclear casein kinase II activity was present in the NHCP fractions as … the capacity of spermine to stimulate (ED50 = 0.19 mM) and heparin to inhibit (ID50 = 0.09 …/ml) the phosphorylation of casein ; further, the phosphotransferase activity could be purified by … casein-agarose and spermine-agarose affinity chromatography.”

“The phosphorylation of both the 55-kDa polypeptide and exogenously added casein was inhibited with GTP, heparin , and 2,3-bisphosphoglycerate in a dose-dependent manner, indicating the involvement of a CK2-like protein kinase.”

“ Heparin stimulated the phosphorylation of poly(EY)4:1 by 2.5-fold, however, it inhibited those of E11G1, poly(EAY)6:3:1, casein and H2B histone.”

“ Casein phosphorylation was significantly inhibited by a high concentration of Mn2+ (greater than 25 mM) or KCl (greater than 100 mM) or by a small amount of heparin (greater than 10 units/mL) and was enhanced about 2-fold by protamine.”

“ Heparin is generally considered a potent and specific inhibitor of casein kinase‐2.”

“The phosphorylation of nucleoplasmin by both kinase preparations is quite insensitive to heparin in contrast with casein phosphorylation which is completely abolished by heparin concentrations above 10 μg/ml.”

“Phosphorylation of acidic substrates such as casein and phosvitin by nuclear protein kinase II is stimulated by polyamines and inhibited by heparin , which mimics an endogenous proteoglycan inhibitor.”

“ Heparin is a potent inhibitor of the kinase when casein , glycogen synthase, or myosin light chain is the substrate.”

“The purified kinase undergoes an autocatalytic reaction resulting in the specific phosphorylation of the beta subunit, … for both ATP and GTP as nucleoside triphosphate donor (17 and 66 microM, respectively), phosphorylates both casein and phosvitin but neither histones nor protamine, modifies … in casein, and is strongly inhibited by heparin (…).”

“256 , 8955–8962 ), has been shown to belong to that class of casein and phosvitin kinases inhibited by heparin.”