Gentamicin and several other aminoglycoside antibiotics in millimolar concentrations directly stimulate the phosphorylation of casein by purified preparations of cAMP- and Ca2+-indenpendent protein kinases PK-C2 (equivalent to cytosolic casein kinase II) and its nuclear counterpart PK-N2 from rat liver and ventral prostate. These stimulatory effects of aminoglycoside antibiotics were similar to those exerted by the aliphatic polyamine spermine. Phosphorylation of casein by purified preparations of messenger-independent protein kinases PK-C1 (equivalent to cytosolic casein kinase I) and its nuclear counterpart PK-N1 was much less enhanced by spermine and the aminoglycoside antibiotics tested. Stimulations of PK-N2 reactions evoked by gentamicin or spermine (at 0.5 and 1.0 mM) were not additive. Several amino sugars tested were without effect on these protein kinases. Methylglyoxal bis(guanylhydrazone) which is known to block the stimulatory effects of polyamines on certain other enzymes did not alter spermine-stimulated phosphorylation of casein catalyzed by PK-N2 preparations.
Bibliographical noteFunding Information:
The skilled technicaal ssistancoef Mr. Alan T. Davis is gratefullya cknowledgedT.h ese studies were supportedi n part by U.S.P.H.S. Research Grant CA-15062 awardedb y the National Cancer Institute,D .H.H.S. and by the U.S. VeteransA d-ministrationM edicalR esearchF und.
- Aminoglycoside antibiotic
- Casein kinase