Polyamines stimulate endogenous protein phosphorylation in thyroid cytosol.
The polyamine, spermine (1-5 mM), when added to rat thyroid cytosol, increases the phosphorylation of a 107 kDa protein 4-fold as analyzed by sodium dodecyl sulfate polyacrylamide gradient gel electrophoresis (SDS-PAGE) and autoradiography; spermidine was less effective and putrescine was without effect. Sodium chloride, when tested at equivalent ionic strengths (4-40 mM), did not reproduce the effects of spermine. In addition to stimulating the phosphorylation of a 107 kDa protein, spermine had an apparent biphasic effect on the phosphorylation of 88 and 65 kDa proteins; maximum stimulation of approximately 60-70% was observed at 0.5-2 mM. Both basal and spermine-stimulated protein phosphorylation patterns were identical whether [gamma-32P] ATP or [gamma-32P] GTP was used as phosphate donors. Heparin (1 microgram/ml) reduced spermine-stimulated phosphorylation of the 107 kDa protein by 64%. Phosphorylation of a 107 kDa protein was not restricted to rat thyroid as spermine was found to augment the phosphorylation of 107 kDa protein(s) in mouse and beef thyroid cytosol preparations.
D000818:Animals; D002417:Cattle; D003600:Cytosol / Q000378:metabolism; D066298:In Vitro Techniques; D051379:Mice; D010766:Phosphorylation; D011073:Polyamines / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013045:Species Specificity; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*
D011073:Polyamines; D011506:Proteins